Theory
Calculation of the information volume of a raster graphic image(the amount of information contained in a graphic image) is based on counting the number of pixels in this image and on determining the color depth (the information weight of one pixel).
When calculating, the formula is used V = i*k,
where V is the information volume of a raster graphic image, measured in bytes, kilobytes, megabytes;
k is the number of pixels (dots) in the image, which is determined by the resolution of the information carrier (monitor screen, scanner, printer);
i is the color depth, which is measured in bits per pixel.
Color depth is given by the number of bits used to encode the color of the point.
The color depth is related to the number of colors displayed by the formula
N = 2i, where N is the number of colors in the palette, i is the color depth in bits per pixel.
Examples
1. The video memory of the computer has a volume of 512Kb, the size of the graphic grid is 640 × 200, in a palette of 8 colors. How many screen pages can fit in the computer's video memory at the same time?
Solution:
Let's find the number of pixels in the image of one page of the screen:
k = 640*200=128000 pixels.
Let's find i (color depth, i.e. how many bits are required to encode one color) N = 2 i , therefore, 8 = 2 i , i = 3.
Find the amount of video memory required to accommodate one page of the screen. V = i * k (bits), V = 3 * 128000 = 384000 (bits) = 48000 (bytes) = 46.875Kb.
Because the computer's video memory is 512Kb, then 512 / 46.875 = 10.923 ≈ 10 whole screen pages can be simultaneously stored in the computer's video memory.
Answer: 10 full pages screen can be simultaneously stored in the computer's video memory
2. As a result of converting a raster graphic image, the number of colors decreased from 256 to 16. How did this change the amount of video memory occupied by the image?
Solution:
We use the formulas V = i * k and N = 2 i .
N 1 = 2 i1 , N 2 = 2 i2 , then V 1 = i 1 * k, V 2 = i 2 * k, therefore,
256 = 2 i1 , 16 = 2 i2 ,
i 1 = 8, i 2 = 4,
V 1 = 8 * k, V 2 = 4 * k.
Answer: the size of the graphic image will be reduced by half.
3. A standard size A4 (21×29.7 cm2) color image is scanned. Scanner resolution is 1200dpi (dots per inch) and color depth is 24 bits. What information volume will have received graphic file?
Solution:
1inch=2.54cm
i=24 bits per pixel;
Let's convert the image dimensions to inches and find the number of pixels k: k = (21/2.54)*(29.7/2.54)*1200 2 (dpi) ≈ 139210118 (pixels)
We use the formula V = i * k
V=139210118*24 = 3341042842 (bits) = 417630355bytes = 407842Kb = 398Mb
Answer: the size of the scanned graphic image is 398 MB
1. Determine the number of colors in the palette at a color depth of 4, 8, 16, 24, 32 bits.
2. In the process of converting a raster graphic image, the number of colors decreased from 65536 to 16. How many times will the information volume of the file decrease?
3. A 256-color drawing contains 120 bytes of information. How many dots does it have?
4. Is 256 Kbytes of video memory enough for the monitor to work in 640x480 mode and with a palette of 16 colors?
5. How much video memory is needed to store two pages of an image, provided that the display resolution is 640 × 350 pixels, and the number of colors used is 16?
6. How much video memory is needed to store four pages of an image if the bit depth is 24 and the display resolution is 800×600 pixels?
7. The amount of video memory is 2 MB, bit depth 24, display resolution 640×480. Which maximum amount pages can be used under these conditions?
8. The video memory has a capacity that can store a 4-color 640×480 image. What size image can be stored in the same amount of video memory, if you use 256 - color palette?
9. Storage bitmap size 1024×512 allocated 256 KB of memory. What is the maximum possible number of colors in an image's palette?
Tasks for calculating volume sound information
Theory
The sound can have different volume levels. The number of different levels is calculated by the formula N = 2 i , where i is the sound depth.
Sampling rate - number of level measurements input signal per unit of time (per second).
The size of a digital mono audio file is calculated by the formula A=D*T*i,
where D is the sampling frequency;
T is the time of sounding or sound recording;
i - bit depth of the register (depth of sound).
For a stereo audio file, the size is calculated by the formula A=2*D*T*i
Solution:
If recording in stereo
A = 2*D*T*i = 44100*120*16 = 84672000bit = = 10584000bytes = 10335.9375Kb = 10.094MB.
If you record a mono signal A = 5Mb.
Answer: 10 Mb, 5 Mb
2. Volume free memory on disk - 0.01 GB, sound card bit depth - 16. What is the duration of the sound of a digital audio file recorded with a sampling rate of 44100 Hz.
Solution:
A = D * T * i
T \u003d 10737418.24 / 44100 / 2 \u003d 121.74 (sec) \u003d 2.03 (min)
Answer: 2.03 min.
Tasks for independent solution
1. Determine the size (in bytes) of a digital audio file whose playing time is 10 seconds at a sampling rate of 22.05 kHz and a resolution of 8 bits. The file is not compressed.
2. The user has a memory of 2.6 MB. You need to record a digital audio file with a duration of 1 minute. What should be the sampling rate and bit depth?
3. The amount of free memory on the disk is 0.01 GB, the bit depth of the sound card is 16. What is the duration of the sound of a digital audio file recorded with a sampling frequency of 44100 Hz?
4. One minute of recording a digital audio file occupies 1.3 MB on the disk, the bit depth of the sound card is 8. At what frequency is the sound recorded?
When choosing flowers, each person thinks about how many flowers should be in the bouquet. After all, in addition to the type and shade of plants, their number plays a big role in the bouquet. With the help of special developments, scientists managed to find out that already in the 5th-6th centuries BC, a certain numerical symbolism was observed. This fact suggests that numbers have a long-verified value, so the number of flowers for a gift should be taken seriously.
Even and odd numbers
According to ancient Slavic traditions, an even number of flowers in a bouquet has the meaning of mourning and charges the bouquet with negative energy.
That is why a paired amount is brought to funerals, to graves or monuments. But residents of Eastern, European countries and the USA have a completely different point of view on this matter. Their even number is a symbol of luck, happiness and love.
The luckiest number in a German bouquet is eight, despite the fact that it is even.
In the United States, 12 flowers are most often given together. Residents of Tokyo will react calmly if you give them 2 flowers each, the main thing is not 4 - this figure is considered a symbol of death for them.
The Japanese, in general, have their own language of plants, and each number has its own meaning. For example, one rose is a sign of attention, three - respect, five - love, seven - passion and adoration, nine - worship. The Japanese present a bouquet of 9 flowers to their idols, and of 7 - to their beloved women. In our country, you can also give an even number of plants if there are more than 15 of them in one set.
The language of flowers
Few people know that the language of flowers determines the number of buds in a bouquet. This language needs to be known and taken into account by the one who makes the gift, so as not to regret their actions in the future. Suddenly, for the recipient, the number of flowers in the bouquet matters.
What the numbers say
An exception to the rule that forbids presenting an even number of flowers is roses, there may even be two.
There is a separate language for these beautiful plants, which defines the meaning for each of their numbers:
How to give a girl a rose
Of course, every woman dreams at least once in her life to receive a large number of roses from her beloved, which will even be difficult to count.
But not always a composition of hundreds of elite plants is more important in terms of love for your chosen one than one beautiful red rose, especially if it is taught correctly.
You should not wrap the flower in a wrapper, and also add extra branches and plants to it, this will only reduce the cost of its appearance.
A rose decorated with a velvet or satin ribbon will look much better. Sometimes you can pack it in a transparent wrapper, but only without too much shine. The same can be said about a bouquet of three buds. If there are more than 7 flowers in the set, then they must be packaged and tied with ribbons so that the bouquet has beautiful view and didn't fall apart.
Visit just about any photography forum and you're bound to stumble upon a discussion about the benefits of RAW and JPEG files. One of the reasons some photographers prefer the RAW format is the greater bit depth (color depth)* contained in the file. This allows you to take photographs of a higher technical quality than what you can get from a JPEG file.
*Bitdepth(bit depth), or colordepth(color depth, in Russian this definition is more often used) - the number of bits used to represent color when encoding one pixel of a raster graphics or video image. Often expressed as a unit of bits per pixel (bpp). Wikipedia
What is color depth?
Computers (and devices that are controlled by embedded computers, such as digital SLR cameras) use the binary system. Binary numbering consists of two digits - 1 and 0 (in contrast to the decimal system, which includes 10 digits). One digit in binary system calculus is called "bit" (English "bit", short for "binary digit", "binary digit").
An 8-bit number in binary looks like this: 10110001 (equivalent to 177 in decimal). The table below shows how this works.
The maximum possible eight-bit number is 11111111 - or 255 in decimal. This is a significant number for photographers because it appears in many imaging programs as well as older displays.
Digital shooting
Each of the millions of pixels in a digital photograph corresponds to an element (also called a "pixel") on the sensor (sensor array) of the camera. These elements, when exposed to light, generate a small electrical current that is measured by the camera and recorded in a JPEG or RAW file.
JPEG files
JPEG files record the color and brightness information for each pixel with three eight-digit numbers, one each for the red, green, and blue channels (these color channels are the same as what you see when plotting a color histogram in Photoshop or on your camera).
Each 8-bit channel records color on a scale of 0-255, providing a theoretical maximum of 16,777,216 shades (256 x 256 x 256). The human eye can distinguish approximately 10-12 million colors, so this number provides more than a satisfactory amount of information for displaying any object.
This gradient was stored in a 24-bit file (8 bits per channel), which is enough to convey a soft color gradation.
This gradient was saved as a 16-bit file. As you can see, 16 bits is not enough to convey a soft gradient.
RAW files
RAW files assign more bits to each pixel (most cameras have 12 or 14 bit processors). More beats - more number, and therefore more tones per channel.
This does not equate to more colors - JPEG files can already record more colors than the human eye can perceive. But each color is preserved with a much finer gradation of tones. In this case, the image is said to have a large color depth. The table below illustrates how bit depth equates to the number of shades.
In-camera processing
When you set the camera to record photos in JPEG mode, the camera's internal processor reads the information received from the sensor at the time you take the picture, processes it according to the parameters set in the camera's menu (white balance, contrast, color saturation, etc.). and writes it as an 8-bit JPEG file. All Additional Information received by the sensor is discarded and lost forever. As a result, you use only 8 bits out of 12 or 14 possible that the sensor is able to capture.
post-processing
A RAW file differs from JPEG in that it contains all the data captured by the camera's sensor during the exposure period. When you process a RAW file using a RAW conversion software, the software will perform the conversions similar topics, which is what the camera's internal processor produces when you shoot in JPEG. The difference is that you set the parameters inside the program you are using, and those set in the camera menu are ignored.
The benefit of the extra bit depth of a RAW file becomes apparent in post-processing. A JPEG file is worth using if you are not going to do any post-processing and you just need to set the exposure and all other settings during shooting.
However, in reality, most of us want to make at least a few adjustments, even if it's just brightness and contrast. And this is exactly the moment when JPEG files start to give way. With less information per pixel, when you make adjustments to brightness, contrast, or color balance, the hues can be visually separated.
The result is most obvious in areas of smooth and long hue transitions, such as in blue skies. Instead of a soft gradient from light to dark, you will see a layering of color stripes. This effect is also known as posterization. The more you adjust, the more it shows up in the image.
With a RAW file, you can make much more dramatic changes to color hue, brightness, and contrast before you see a drop in image quality. It also allows you to do some of the functions of the RAW converter, such as adjusting the white balance and restoring "overexposed" areas (highlight recovery).
This photo was taken from a JPEG file. Even at this size, stripes in the sky are visible as a result of post-processing.
Upon closer examination, the effect of posterization is visible in the sky. Working with a 16-bit TIFF file can eliminate, or at least minimize, the banding effect.
16-bit TIFF files
When you process a RAW file, your software gives you the option to save it as an 8 or 16 bit file. If you're happy with the processing and don't want to make any more changes, you can save it as an 8-bit file. You won't notice any difference between an 8 bit file and a 16 bit file on your monitor or when you print the image. The exception is if you have a printer that recognizes 16-bit files. In this case, you can get better results from a 16 bit file.
However, if you plan to post-process in Photoshop, then it is recommended that you save the image as a 16-bit file. In this case, an image taken from a 12 or 14 bit sensor will be "stretched" to fill the 16 bit file. After that, you can work on it in Photoshop, knowing that the extra color depth will help you achieve maximum quality.
Again, when you have completed the processing process, you can save the file as an 8-bit file. Magazines, book publishers and stocks (and just about any customer who buys photographs) require 8-bit images. 16 bit files are only required if you (or someone else) intend to edit the file.
This is an image I took using the RAW+JPEG setting on the EOS 350D. The camera saved two versions of the file - a JPEG file processed by the camera's processor, and a RAW file containing all the information recorded by the camera's 12-bit sensor.
Here you can see a comparison of the upper right corner of the processed JPEG file and the RAW file. Both files were created by the camera with the same exposure setting and the only difference between them is the color depth. I was able to “pull out” the “overexposed” details in the JPEG that are not distinguishable in the RAW file. If I wanted to work on this image further in Photoshop, I could save it as a 16-bit TIFF file to ensure the best possible image quality during the processing.
Why do photographers use JPEG?
The fact that not all professional photographers use the RAW format all the time doesn't mean anything. Both wedding and sports photographers, for example, often work with the JPEG format.
For wedding photographers who can shoot thousands of shots at a wedding, this saves time on post-production.
Sports photographers use JPEG files to be able to send photos to their graphic editors during the event. In both cases, the speed, efficiency, and smaller file size of the JPEG format make it a logical file type to use.
Color depth on computer screens
Bit depth also refers to the color depth that computer monitors are capable of displaying. The reader using modern displays It may be hard to believe, but the computers I used in school could only reproduce 2 colors - white and black. "Must-have" computer of that time - Commodore 64, capable of reproducing as many as 16 colors. According to information from Wikipedia, more than 12 units of this computer have been sold.
Commodore 64 computer. Photo by Bill Bertram
Undoubtedly, you will not be able to edit photos on a machine with 16 colors (64 Kb random access memory anyway), and the invention of true-to-life 24-bit displays is one of the things that made digital photography possible. Displays with true-to-life color reproduction, just like JPEG files, are formed using three colors (red, green, and blue), each with 256 shades, stored in an 8-bit digit. Most modern monitors use either 24-bit or 32-bit true-to-life color graphics.
HDR files
Many of you know that High Dynamic Range (HDR) images are created by combining multiple versions of the same image taken from different settings exposure. But did you know that the software generates a 32-bit image with over 4 billion tonal values per channel per pixel - just a jump from the 256 tones in a JPEG file.
True HDR files cannot be displayed correctly on a computer monitor or printed page. Instead, they are trimmed down to 8 or 16-bit files using a process called tone-mapping, which retains the high dynamic range characteristics of the original image, but allows it to be played back on devices with a narrow dynamic range.
Conclusion
Pixels and bits are the basic elements for building a digital image. If you want to get the best possible image quality from your camera, you need to understand the concept of color depth and the reasons why the RAW format produces the best image quality.
"Bitness" is one of the parameters that everyone is chasing, but few photographers really understand it. Photoshop offers 8, 16, and 32-bit file formats. Sometimes we see files marked as 24 and 48-bit. And our cameras often offer 12 and 14 bit files, although you can get 16 bit with a medium format camera. What does it all mean, and what does it really matter?
What is bit depth?
Before comparing various options, let's first discuss what the name means. A bit is a computer unit of measure referring to the storage of information as 1 or 0. One bit can only have one of two values: 1 or 0, yes or no. If it were a pixel, it would be completely black or completely white color. Not very helpful.
In order to describe a more complex color, we can combine several bits. Every time we add bits, the number of potential combinations doubles. One bit has 2 possible values 0 or 1. When 2 bits are combined, you can have four possible values (00, 01, 10 and 11). When you combine 3 bits, you can have eight possible values (000, 001, 010, 011, 100, 101, 110 and 111). And so on. In general, the number of possible choices will be the number two raised to the power of the number of bits. So "8-bit" = 2 8 = 256 possible integer values. In Photoshop, this is represented as integers 0-255 (internally, it's binary 00000000-11111111 for a computer).
So "bit depth" defines the smallest changes you can make, relative to some range of values. If our gray scale from pure black to pure white has 4 values that we get from 2-bit color, then we will be able to use black, dark gray, light gray and white. It's pretty small for photography. But if we have enough bits, we have enough steps with a wide range of grays to create what we'll see as a perfectly smooth black to white gradient.
Below is an example of comparing a black to white gradient at different bit depths. This image is just an example. Click on it to see the image in full resolution in JPEG2000 format up to 14 bits. Depending on the quality of your monitor, you will probably only be able to see the difference up to 8 or 10 bits.
How to understand bit depth?
It would be nice if all "bit depths" could be compared directly, but there are some terminology differences that need to be understood.
Please note that the image above is black and white. A color image is usually made up of red, green, and blue pixels to create color. Each of these colors is treated as a "channel" by the computer and monitor. Software, such as Photoshop and Lightroom, count the number of bits per channel. So 8 bits means 8 bits per channel. This means that an 8-bit RGB image in Photoshop will have a total of 24 bits per pixel (8 for red, 8 for green, and 8 for blue). A 16-bit RGB or LAB image in Photoshop will have 48 bits per pixel, and so on.
You might assume that 16-bit means 16-bit per channel in Photoshop, but in this case it works differently. Photoshop actually uses 16 bits per channel. However, it treats 16-bit snapshots differently. It just adds one bit to 15 bits. This is sometimes called 15+1 bits. This means that instead of 2 16 possible values (which would equal 65536 possible values), there are only 2 15+1 possible values, which is 32768+1=32769.
So, in terms of quality, it would be fair to say that Adobe's 16-bit mode actually contains only 15-bit. You do not believe? Look at the 16-bit scale for Photoshop's Info panel, which shows a scale of 0-32768 (meaning 32769 values given zero. Why is Adobe doing this? According to Adobe developer Chris Cox, this allows Photoshop to work much faster and provides an accurate midpoint for range, which is useful for blending modes.
Most cameras will let you save files in 8-bit (JPG) or 12 to 16-bit (RAW). So why doesn't Photoshop open a 12 or 14 bit RAW file like 12 or 14 bit? On the one hand, it would require a lot of resources to Photoshop work and changing file formats to support other bit depths. And opening 12-bit files as 16-bit isn't really any different than opening an 8-bit JPG and then converting to 16-bit. There is no immediate visual difference. But most importantly, there are huge benefits to using a file format with a few extra bits (as we'll discuss later).
For displays, terminology varies. Manufacturers want their equipment to sound enticing. That's why 8-bit display modes are usually labeled "24-bit" (because you have 3 channels of 8-bit each). In other words, "24-bit" ("True Color") for a monitor is not very impressive, it actually means the same as 8-bit for Photoshop. The best option it would be "30-48 bits" (called "Deep Color"), which is 10-16 bits per channel, although for many more than 10 bits per channel is overkill.
How many bits can you see?
With a pure gradient (i.e. the worst conditions), many can detect banding in a 9-bit gradient that contains 2048 shades of gray on a good display with support for deeper color display. The 9-bit gradient is extremely weak, barely perceptible. If you didn't know it existed, you wouldn't see it. And even when you look at it, it will not be easy to tell where the borders of each color are. An 8-bit gradient is relatively easy to see if you look at it closely, although you can still miss it if you don't look closely. Thus, we can say that a 10-bit gradient is visually identical to a 14-bit gradient or deeper.
Note that if you want to create your own file in Photoshop, the gradient tool will create 8-bit gradients in 8-bit document mode, but even if you convert the document to 16-bit mode, you will still have 8-bit gradient. However, you can create a new gradient in 16-bit mode. However, it will be created in 12-bit. The program doesn't have a 16-bit option for Photoshop's gradient tool, but 12-bit is more than enough for any practical work, since it allows 4096 values.
Don't forget to enable anti-aliasing in the gradient panel, as this is best for testing.
It is also important to note that you are likely to experience false banding when viewing images at less than 67% magnification.
Why use more bits than you can see?
Why do we have options even more than 10-bit in our cameras and Photoshop? If we didn't edit the photos, then there would be no need to add more bits than the human eye can see. However, once we start editing photos, previously hidden differences can easily come to light.
If we significantly lighten the shadows or darken the highlights, then we will increase some of the dynamic range. And then any shortcomings will become more obvious. In other words, increasing the contrast in an image works like decreasing bit depth. If we turn the parameters up enough, banding may appear in some areas of the image. It will show transitions between colors. Such moments usually become noticeable in clear blue skies or in shadows.
Why do 8-bit images look the same as 16-bit ones?
When converting a 16-bit image to 8-bit, you won't see the difference. If so, then why use 16-bit?
It's all about smooth editing. When working with curves or other tools, you will get more adjustment steps for tones and colors. Transitions will be smoother at 16 bits. Therefore, even if the difference may not be initially noticeable, the transition to a lower color bit depth can become a serious problem later when editing the image.
So how many bits do you really need in a camera?
A change of 4 stops in will provide a loss of just over 4 bits. A change of 3 stops of exposure is closer to a loss of 2 bits. How often do you have to adjust the exposure so much? When working with RAW, correcting up to +/- 4 stops is an extreme and rare situation, but it happens, so it is desirable to have an additional 4-5 bits above the limits of the visible range in order to have headroom. With a normal range of 9-10 bits, with a margin, the norm can be approximately 14-15 bits.
In fact, you will probably never need that much data for several reasons:
- There are not many situations where you will encounter the perfect gradient. Clear blue skies are probably the most common example. All other situations have a lot of detail and color transitions are not smooth, so you won't see the difference when using different bit depths.
- Your camera's accuracy is not high enough to ensure color accuracy. In other words, there is noise in the image. This noise usually makes it much harder to see the transitions between colors. It turns out that real images are usually not able to display color transitions in gradients, since the camera is not able to capture the perfect gradient that can be created programmatically.
- You can remove color transitions in post-processing by using a Gaussian blur and adding noise.
- A large supply of bits is needed only for extreme tonal corrections.
All things considered, 12-bit sounds like a very reasonable level of detail that would allow for some great post-processing. However, the camera and the human eye react differently to light. The human eye is more sensitive to shadows.
An interesting fact is that a lot depends on the program you use for post-processing. For example, pulling shadows from the same image in Capture One (CO) and in Lightroom can produce different results. In practice, it turned out that CO spoils deep shadows more than its counterpart from Adobe. Thus, if you draw in LR, you can count on 5 stops, and in CO - only 4.
Still, it's best to avoid trying to stretch more than 3 stops of dynamic range due to noise and color shift. 12-bit is definitely a smart choice. If you care about quality over file size, shoot in 14-bit if your camera allows it.
How many bits does it cost to use in Photoshop?
Based on the above, it should be clear that 8-bit is not enough. You can immediately see the color transitions in smooth gradients. And if you don't see it right away, even modest adjustments can make the effect noticeable.
Worth working in 16 bit even if your original file 8-bit, such as JPG images. The 16-bit mode will give the best results because it will minimize transitions when editing.
There is no point in using 32-bit mode if you are not processing an HDR file.
How many bits do you need for the internet?
The advantages of 16 bits are in the expansion of editing possibilities. Converting the final edited image to 8 bit is great for viewing snapshots and has the advantage of creating small files for the web for more fast loading. Make sure anti-aliasing is enabled in Photoshop. If you use Lightroom to export to JPG, anti-aliasing is used automatically. This helps add some noise, which should minimize the risk of noticeable 8-bit color transitions.
How many bits are needed to print?
If you print at home, you can simply create a copy of a working 16-bit file and process it for printing by printing the working file. But what if you send your images over the internet to a lab? Many will use 16-bit TIF files and this is a great way to go. However, if your print requires JPG or you want to send a smaller file, you may run into questions about switching to 8-bit.
If your print lab accepts 16-bit format (TIFF, PSD, JPEG2000), just ask the experts which files are preferred.
If you need to send a JPG it will be in 8 bit but that shouldn't be a problem. In fact, 8-bit is great for final print output. Just export files from Lightroom at 90% quality and Adobe RGB color space. Do all the processing before converting the file to 8 bits and there will be no problems.
If you don't see color banding on your monitor after converting to 8-bit, you can be sure that everything is in order for printing.
What is the difference between bit depth and color space?
The bit depth determines the number of possible values. The color space defines the maximum values or range (commonly known as "gamma"). If you need to use a box of colored pencils as an example, more bit depth will be expressed as more shades, and more range will be expressed as richer colors regardless of the number of pencils.
To see the difference, consider the following simplified visual example:
As you can see, by increasing the bit depth we reduce the risk of color banding. By expanding the color space (wider gamut) we can use more extreme colors.
How does color space affect bit depth?
SRGB (left) and Adobe RGB (right) The color space (the range over which the bits are applied), so a very large gamut can theoretically cause banding associated with color transitions if it is stretched too much. Remember that bits determine the number of transitions in relation to the color range. Thus, the risk of getting visually noticeable transitions increases with the expansion of the gamut.
Recommended settings to avoid banding
After all this discussion, we can conclude in the form of recommendations that should be followed in order to avoid problems with color transitions in gradients.
Camera settings:
- 14+ bit RAW file is good choice, if you want to, best quality, especially if you're looking to make adjustments to tone and brightness, such as increasing the brightness in shadows by 3-4 stops.
- A 12-bit RAW file is great if you want to have smaller file sizes or shoot faster. For a Nikon D850 camera, a 14-bit RAW file is about 30% larger than a 12-bit one, so this is an important factor. And large files may affect the ability to shoot long series of frames without overflowing the memory buffer.
- Never shoot in JPG if you can. If you shoot some events when you need to quickly transfer files and the quality of the pictures does not matter, then of course Jpeg will great option. You may also want to consider shooting in JPG+RAW mode if you need a higher quality file later on. It's worth sticking to the SRGB color space if you're shooting in JPG. If you shoot in RAW, you can ignore the color space settings. RAW files don't really have a color space. It is not installed until the RAW file has been converted to another format.
Lightroom and Photoshop (working files):
- Always save working files in 16-bit. Use 8 bits only for final export to JPG format for the web and print, if the format meets the requirements of the printing equipment. It is OK to use 8-bit for final output, but this mode should be avoided during processing.
- Be sure to view the image at 67% or larger to ensure that there are no noticeable color transitions in the gradients. On a smaller scale, Photoshop can create false banding. This will be our other article.
- Be careful when using HSL in Lightroom and Adobe Camera RAW as this tool can create color bands. This has very little to do with bit depth, but problems are possible.
- If your source file is only available in 8-bit (eg JPG), you must immediately convert it to 16-bit before editing. Subsequent edits on 8-bit images in 16-bit mode will not create too obvious problems.
- Don't use 32-bit unless you're using it to merge multiple RAW (HDR) files. There are some limitations when working in 32-bit space, and the files become twice as large. It's best to do HDR merging in Lightroom instead of using Photoshop's 32-bit mode.
- The HDR DNG format of Lightroom is very handy. It uses 16-bit floating point mode in order to cover a wider dynamic range with the same number of bits. Considering that we usually only need to correct HDR dynamic range within 1-2 stops, this is an acceptable format that improves quality without creating huge files. Of course, don't forget to export this RAW as a 16-bit TIF/PSD when you need to continue editing in Photoshop.
- If you're one of the few people who must use 8-bit operating mode for some reason, it's probably best to stick with the sRGB color space.
- When using the gradient tool in Photoshop, checking the "smooth" option will cause the program to use 1 extra bit. This can be useful when working with 8-bit files.
Export for web:
- JPG with 8 bits and sRGB color space is ideal for the web. While some monitors are capable of displaying greater bit depth, the increased file size is probably not worth it. And while more and more monitors support wider gamuts, not all browsers properly support color management and may display images incorrectly. And most of these new monitors have probably never been color calibrated.
- 8-bit is fine for final print output, but use 16-bit if your printing hardware supports it.
- A standard monitor will be fine for most purposes, but be aware that you may see color streaks due to 8-bit displays. These bands may not actually be in the pictures. They appear at the stage of output to the monitor. The same picture may look better on a different display.
- If you can afford it, a 10-bit display is perfect for photography. A wide range such as Adobe RGB is also ideal. But this is optional. You can create amazing pictures on the most ordinary monitor.
A look into the future
AT this moment choosing a higher bit depth may not matter to you since your monitor and printer are only 8 bit capable, but things may change in the future. Your new monitor will be able to display more colors and print on professional equipment. Save your working files in 16-bit. This will be enough to keep the best quality for the future. This will be enough to meet the requirements of all monitors and printers that will appear in the foreseeable future. This range of color is enough to go beyond the range of human vision.
However, gamma is different. Most likely, you have a monitor with sRGB color gamut. If it supports the wider Adobe RGB spectrum or the P3 gamut, then you're better off working with those gamuts. Adobe RGB has an extended color range in blues, cyan, and greens, while P3 offers wider colors in reds, yellows, and greens. In addition to P3 monitors, there are commercial printers that exceed the AdobeRGB gamut. sRGB and AdobeRGB are no longer able to capture the full range of colors that can be recreated on a monitor or printer. For this reason, it's worth using a wider range of colors if you're looking to print or view your pictures on better printers and monitors later. For this, the ProPhoto RGB gamma is suitable. And, as discussed above, a wider gamut needs more 16-bit bit depth.
How to remove banding
But if you encounter banding (most likely when going to an 8-bit image), you can take the following steps to minimize this problem:
- Convert the layer to a smart object.
- Add a Gaussian blur. Set the radius to hide the banding. A radius equal to the banding width in pixels is ideal.
- Use a mask to apply blur only where needed.
- And finally add some noise. Grain eliminates the appearance of smooth blur and makes the image more cohesive. If you're using Photoshop CC, use the Camera RAW filter to add some noise.
When ordering printing on packages, it is recommended to apply simple images for execution in no more than one or three colors. It is worth noting that when creating a layout by a good designer, this will not affect the quality and perception of the advertising information provided by the consumer, and in addition, it will reduce the cost and terms of order production. You should also take into account the possibility of combining colors in the technological plan and select the appropriate equipment. After all, not all applied images are geometrically independent of each other, often some colors are rigidly interconnected and they need to be joined.
If you still need a drawing with a large number of different colors, then it is better to use special equipment that allows you to perform full color printing on bags. The principle of such machines is the presence of UV drying, since only UV-curable inks can be used for full-color printing. Of course this technology implies not only the high cost of printing full-color images on the package, but also printing larger dots, so you should not expect the quality of the picture, as on paper.
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