robertdfeinman
Robert Feinman
Most procedures aimed at improving color fidelity in prints are concerned with "white balance" or achieving a neutral gray.
Modern digital cameras frequently have options to do this automatically. For film shooters there has been the old trick of including a gray card in the scene or in an extra frame.
These techniques may insure that the biggest deviations from neutrality are compensated for, but this does not mean that all colors will be reproduced properly.
I'd like to suggest a more thorough technique.
The first thing needed is to obtain a color swatch book such as those offered by Pantone. I'm not aware of any product which does exactly what I'm going to propose, but maybe some entrepreneur will step up. The "book" that I envision would consist of a series of cards attached in one corner which can be fanned out. Each color would have an identifying label as well.
When photographing a scene one would find swatches in the pack that match key colors in the scene and note which these are. For a landscape this might be the grass and the sky. For a portrait the skin tone and some clothing colors.
For those shooting digitally, one would take a photo of the key swatches arranged in a fan so as to capture them all at once, along with the actual scene. Film shooters can just note the swatches by number, or can also take a picture of them on a separate frame.
Back at the computer one then edits the image while comparing the image to the swatch book. Using selective color adjustments match the key colors to the samples. Before doing this one needs to decide what the aim of color fidelity is.
There are two ways of viewing a scene. For a typical scene in daylight we regard the color of the illumination as "white" and expect the colors to appear natural. This is what "white balance" tries to achieve. However, when a scene is illuminated by other light sources the color is not the same. For example, in shade the light is bluish, since it is mainly from the sky. Our eyes tend to adjust for this so we don't see the color shift. In a scene which is both in sun and shade we may notice that the shadows are bluish. Similarly during the late evening the sun is low and the color is yellowish. Making the scene "normal" would eliminate all the characteristic late day color.
Is the final image to appear as if it was illuminated by "white" light or is it to retain the color shift of the source? If one wants it to look normal than the first step is to remove any color cast using standard gray balancing techniques. Then one can follow by adjusting the individual colors by comparing them to the swatches. Adjust the color swatch image using a series of adjustment layers (I prefer the curves tool for almost all corrections). Then drag these adjustment layers to the real image. If you have made masked color adjustment layers which alter only a selective color then save the curve, make a new mask in the real image that encompasses the desired areas and reload the proper curve.
This procedure will make the colors look natural and remove the distortion caused by the color of the light source. It is useful, not only in open shade, but when there is strong reflection off adjacent foliage and indoors when using non-photographic lighting.
On the other hand if one wants to keep the color shift caused by the source then gray balance step should be skipped and only the needed individual colors be adjusted. The way to do this is to make a temporary adjustment layer to set the gray balance to neutral and then add the individual color adjustment layers as needed to the swatch image. After the relative colors have been matched to the swatches the temporary layer is eliminated, or disabled. Copy the individual adjustments to the final image as before, but without the overall color balance layer.
It is possible that totally eliminating all signs of gray scale balancing will make the image appear too far off in color balance. This is because our eyes are constantly trying to "white balance" a scene even when it is as far off color as a sunset, so adding a slow amount of gray adjustment may be needed to make things look more natural. Using the gray balance layer, but with a reduced opacity may be the easiest way.
Film shooters who only note the swatch values, but don't photograph the fan will not be able to do a completely accurate natural balance, but will have to rely on an approximation to set the gray balance. Fortunately the gray balance eyedropper tool in Photoshop usually does a reasonably good job, as long as there is something in the scene that should appear neutral. Some of the auto balance options also work well when scenes have a good range of colors.
A less perfect method, which one can do now with present equipment, is to shoot a GretagMacbeth Color Checker chart and then select swatches which are near to the key colors in the scene to adjust. Only you know the purpose of the final photo and the degree of fidelity required. Advertisers are very fussy about getting the colors of their products reproduced accurately. Those making pictures for other reasons will have to decide for themselves.
Modern digital cameras frequently have options to do this automatically. For film shooters there has been the old trick of including a gray card in the scene or in an extra frame.
These techniques may insure that the biggest deviations from neutrality are compensated for, but this does not mean that all colors will be reproduced properly.
I'd like to suggest a more thorough technique.
The first thing needed is to obtain a color swatch book such as those offered by Pantone. I'm not aware of any product which does exactly what I'm going to propose, but maybe some entrepreneur will step up. The "book" that I envision would consist of a series of cards attached in one corner which can be fanned out. Each color would have an identifying label as well.
When photographing a scene one would find swatches in the pack that match key colors in the scene and note which these are. For a landscape this might be the grass and the sky. For a portrait the skin tone and some clothing colors.
For those shooting digitally, one would take a photo of the key swatches arranged in a fan so as to capture them all at once, along with the actual scene. Film shooters can just note the swatches by number, or can also take a picture of them on a separate frame.
Back at the computer one then edits the image while comparing the image to the swatch book. Using selective color adjustments match the key colors to the samples. Before doing this one needs to decide what the aim of color fidelity is.
There are two ways of viewing a scene. For a typical scene in daylight we regard the color of the illumination as "white" and expect the colors to appear natural. This is what "white balance" tries to achieve. However, when a scene is illuminated by other light sources the color is not the same. For example, in shade the light is bluish, since it is mainly from the sky. Our eyes tend to adjust for this so we don't see the color shift. In a scene which is both in sun and shade we may notice that the shadows are bluish. Similarly during the late evening the sun is low and the color is yellowish. Making the scene "normal" would eliminate all the characteristic late day color.
Is the final image to appear as if it was illuminated by "white" light or is it to retain the color shift of the source? If one wants it to look normal than the first step is to remove any color cast using standard gray balancing techniques. Then one can follow by adjusting the individual colors by comparing them to the swatches. Adjust the color swatch image using a series of adjustment layers (I prefer the curves tool for almost all corrections). Then drag these adjustment layers to the real image. If you have made masked color adjustment layers which alter only a selective color then save the curve, make a new mask in the real image that encompasses the desired areas and reload the proper curve.
This procedure will make the colors look natural and remove the distortion caused by the color of the light source. It is useful, not only in open shade, but when there is strong reflection off adjacent foliage and indoors when using non-photographic lighting.
On the other hand if one wants to keep the color shift caused by the source then gray balance step should be skipped and only the needed individual colors be adjusted. The way to do this is to make a temporary adjustment layer to set the gray balance to neutral and then add the individual color adjustment layers as needed to the swatch image. After the relative colors have been matched to the swatches the temporary layer is eliminated, or disabled. Copy the individual adjustments to the final image as before, but without the overall color balance layer.
It is possible that totally eliminating all signs of gray scale balancing will make the image appear too far off in color balance. This is because our eyes are constantly trying to "white balance" a scene even when it is as far off color as a sunset, so adding a slow amount of gray adjustment may be needed to make things look more natural. Using the gray balance layer, but with a reduced opacity may be the easiest way.
Film shooters who only note the swatch values, but don't photograph the fan will not be able to do a completely accurate natural balance, but will have to rely on an approximation to set the gray balance. Fortunately the gray balance eyedropper tool in Photoshop usually does a reasonably good job, as long as there is something in the scene that should appear neutral. Some of the auto balance options also work well when scenes have a good range of colors.
A less perfect method, which one can do now with present equipment, is to shoot a GretagMacbeth Color Checker chart and then select swatches which are near to the key colors in the scene to adjust. Only you know the purpose of the final photo and the degree of fidelity required. Advertisers are very fussy about getting the colors of their products reproduced accurately. Those making pictures for other reasons will have to decide for themselves.