Color Management

Color management is the practice of controlling the quality of your images through use of various tools in a multitude of programs. Color management is dealing primarily with the control of color, contrast, saturation, and exposure of the image. Some areas of concern are.

White Balance: Or color temperature. This determines the overall cast of the image. The white balance setting when taking the photo with the camera will determine the processes the camera applies to the original image. If shooting in RAW you will be able to alter it to whatever you would like later. If shooting in jpeg, then you are stuck with the setting.

Contrast: Contrast deals with the range of white to black in the image. Low contrast will have a wide range of tones and sometimes not have a true white or black. High contrast will have an absolute black and white within the image, but very little tonal range in between the two.

Exposure: This is determined by the initial settings on the camera when shooting. It can be adjusted somewhat when shooting in Raw, not in jpeg. The exposure will determine the amount of detail available with the image. An over exposed image will have blown out highlights with no detail and no real chance of bring them back. An under exposed image will have highlight detail, but none in the shadows and will normally have some “noise” associated with the d-min areas. You can add some more density to the shadows, but the detail will no be there.

Saturation: This deals with the intensity of the colors in the image. Zero saturation will be B/W. Be careful with using saturation usage. Over saturating an image will give bad transitions and can create an unrealistic look.

Raw Vs Jpeg
Jpeg is a lossy format for digital imaging. In order to compress the file to save storage space, the algorithm for jpeg takes a sampling of the areas around each pixel and “combines” similar ones together. The lower the quality setting, the more liberal it is with judgment on similarities and will compress the image info more. When you open the image, the algorithm is reversed and detail filled back in. As with any mathematical equation, there will be slight variations every time you open, make changes and resave. Detail can be lost over time when working on images multiple times. This is what makes it a lossy format. When shooting in jpeg, you are already not recording all the information that your camera is capable of obtaining due to the compression of the files generated.

Raw is the native format for digital camera. It is the equivalent to having a digital negative in terms of correction ability. As the name implies, Raw is nothing but the raw data the camera captures for any image regardless of any settings beyond exposure you might have set. An under or over exposed image is still under or over exposed in Raw and will suffer accordingly.
The advantage is that any other processing the camera would have done is still an option in post production. White balance can be completely changed from what was shot, and the image will appear as if it had been shot that way initially.
Raw records the maximum amount of data possible from your camera. It will generate the largest size file also. When shooting, it is best to shoot in Raw and then convert with corrections to a printable format. Printers will not print from a Raw file. Each camera model does have it’s own unique tag on the Raw file that will require either the camera software for conversion or that Photo Shop has the tag for it. When new cameras come out, you will be able to download an update for the tag.



Color Space
sRGB is a color space developed by HP and Microsoft to best simulate the colors available in web based imaging. It is a limited color space that is designed to look good on the lowest common denominator monitors in use. SRGB encompasses about 35% of the visible colors in its range

Adobe 1998 RGB was developed by Adobe to be worked in for the color range that is reproducible in the photographic field. It has 50% of the visible colors available in its gamut, for about a 50% increase in the palate. The colors most affected by the increase are deep greens brighter magentas and oranges (skin tones fall here), and more subtle variations in high tones. Again the Adobe 1998 RGB will capture more data for you when shooting. If you want to discard it later, then you will have the option.

Choosing a color space to shoot in is only a factor when shooting in jpeg. When shooting in Raw the camera will automatically capture the highest amount of information. When converting the files to a printable format is when you will want to decide whether to choose sRGB or Adobe 1998 RGB

8 bit vs. 16 bit

What is a bit

A bit is the amount of information assigned to a pixel in terms of color value. An 8 bit image will have 256 color values assigned to it and a 16 bit image will have 4096 color values assigned to it. This will produce a smother gradation through color blends. Some of these are not even visible to the human eye, and only a very few printers can even process a 16 bit image to output. Not really worth the effort since there is no feasible way to handle the output, and with very rare exceptions will you even be able to tell the difference.




Tools for Dealing with Color Management

For this class we will be dealing with the tools used in Photoshop. These tools are available in all versions of Photoshop.

Levels: (ctrl+L) Levels work with Histograms which are a graph of the exposure values in the image. The right end is the highlights, the left is shadow and there will be a slider in the middle to control midtones. This is a general overall tool. You will be able to bring the highlights slider to the start of detail in the image, bring the shadow slider to the ending of detail and do an overall adjustment to the midtones. It is a limited tool that will not allow you to isolate a specific range in the tones for adjustment.

Curves: (ctrl+M) This is the most useful tool overall. With curves you will be able to isolate a very specific range of tones in the image and adjust them without affecting the rest. You will also be able to make corrections to the individual color channels independently of each other.

Color Balance: (ctrl+B)A good tool for adjusting overall casts, not very useful for dealing with specific colors. The slider bar interface allows you to adjust the entire image, but not isolate a specific range.

Selective Color: Very good tool for correcting a color shift within a specific color group (I.e red, green, blue, etc…) Simply select the color you want to adjust then using the slider bars adjust the cast of it. A good use is when there is an individual with a very red complexion while everyone else is normal. To adjust the complexion, just select the red color to correct in the pull down menu, go to the magenta slider and take some out. Since the person’s skin is red and not the other people, just his complexion will be affected. Be careful though, if someone is wearing a red outfit it will be affected too.

Chanel Mixer: This tool allows you to mix in detail and density from one color channel to another (I.e red into green). This can be useful for dealing with an overall cast, but is a heavy handed tool with no finesse to it. A very little of this tool goes a very long way.

Hue / Saturation: Great tool for what it does. Basically this tool allows you to increase or decrease the intensity of the colors in the image. An image with a very strong cross cast, such as a red highlight and cyan shadows, can be helped by lowering the saturation to even out the tones. You can also increase the saturation to bring out muted colors on an overcast day, or brighten up fall colors and sunsets even more. Be very careful not to over saturate colors. Skin tones can quickly become blotchy and unnatural.

Shadow Highlight: Perhaps one of the most useful tools in the adjustment menu. What this tool does is equalize the exposure values between highlights and shadows. There are slider bars (also use the expanded options window) that let you control the amount of highlight and shadow equalization going on. Take some practice to find good balances, there are no written in stone numbers to enter in since each image will have it’s own set of problems to fix.

Brightness / Contrast: Simply adjust the brightness and or the contrast via two slider bars. Much finer and more precise control using curves.

Desaturate: (Shift+ctrl+U) Averages all the color values of the bit depth of the pixel to create a grey scale image.

Match Color: Used to match colors from one image to another. Be very careful when using this tool. The color to match and the color to match it to must be picked very carefully. Due to shading that occurs on images, just being slightly off on the density of the two spots you are choosing can result in very different overall images.

Replace color: Used to replace one color with another. Again, be very careful with this. The color you are choosing to replace might be slightly present in another area (such as skin tones) that you do not want to alter.

Variations: Can be somewhat useful when first starting off. The variations option will show you the image as it is right now and then create a series of corrected images around it with color and density variations. You choose the one you like best and it then creates a new series of variations based off of that choice. You keep selecting a variation until the one that is the standard in the ring is what you want.

There are other options in the Adjustment menu, most are used for working in layers and will be covered in other classes.

Image Modes

What are image modes

Image modes options are different ways to save or present the information in the image.

Bitmap: Very low rez and incredibly limited colors. Just stay away from unless it is text only.

Greyscale: A B/W image with no color information at all.

Doutone: A two channel image consisting on two separate colors. These can be any two colors you want. Some sepia tone images us this mode with a brown color and a black channel to ad depth to the shadows.

RGB: The preferred mode for photographers This mode has three channels consisting of Red Green and Blue that are mixed together for form all the other colors. This creates the widest range of colors usable by printers, monitors, and visible by the human eye. This is an additive color space that deals with light mixing. In other words, if you ad equal amounts of each color of RGB you will get white. This is how film and photo paper work.

CMYK: The color space used by the printing press industry utilizing inks, or reflective colors that absorb color rather than light that generates it. This is a subtractive space that ads colors to create black.

LAB: A space specifically designed for digital imaging. The three channels deal with light (or luminescence), color and two channels dealing with color casts and contrast.

Indexed Color: A conversion dealing with assigning a profile to the image that will be used for a very specific process later, such as for a printing press with certain characteristics. No need to use with photography.

Multi Channel: CMYK with out a K (black) channel. Produces a very washed out image. The reason for this deals strictly with pre press applications for printing on offset presses. Will never be used in photography except for the incredibly rare times it might be useful in creating masking channels. Not even worth discussion.

Other controls

In programs such as Lightroom, Bridge, and other RAW conversion engines you will have some other non color related options to mull over. Here is a list of some of them and what to do with them.

Contrast: Controls the starkness of the image. Or to phrase it differently, the quickness for pure black to pure white. A low contrast will have a wider gamut of tones and might even be lacking in a true black or white. These images are often called muddy or flat. Contrasty images will be lacking in gradation between density ranges. Blacks will often be blocked up and highlights can quickly become blown out. Find the right level for the image. There is no ideal setting though, each image will vary from lighting situation to lighting situation.

Clarity: Sometimes also called detail. This is a localized contrast variable used to create a stronger differential between densities giving an illusion of finer detail being shown. A little goes a long way with this tool. Setting your Clarity too high will result in jaggy lines around some areas, so keep an eye on it.

Sharpness: This is another contrast differential tool, but on a more global scale than Clarity. Again be very careful with this tool as over usage will quickly result in pixilated detail. Stepping will occur first in finer lined detail such as hair and eyes. There is no way to bring an out of focus image into clear focus. I really don’t care what they show being done on TV shows, it isn’t possible. If detail is not in the original image, there is no way to create what is not there. Sharpness will, however, make an already focused image razor sharp.