Black Point Parameters
Selecting an appropriate black point determines the tonal range of the image. By properly placing the black point, the image should reproduce as a full-tonal scale image. The RGB values used for black point placement are more subjective than with white point selection. You can control the amount of shadow detail by using higher or lower settings for the black point value. Please see the Black Point Setting section to understand how the black point setting can be used to adjust the tonal range and detail in the shadows.
A Note about Black Point Compensation
Many people believe that black point compensation (a print driver setting option) will handle the black point placement. Tests have shown us that this is not true. Taking the time to properly set the black point will give you much greater control over the tonal range and shadow detail of your images.
Proper Black Point Selection
A proper black point must meet one or more of these three criteria.
- The black point should be neutral or as close to neutral is possible.
- The black point must be the darkest value in the image.
- It must be just lower in value than the darkest part of the image you
want a visible separation in the shadow values.
The neutrality of a shadow can be an issue because shadows are often filled with reflected light, usually blue from the sky. There is a way to compensate for this in the color correcting process. Please see the Black Point Setting section for more information.
Again, the RGB values of the black point can be varied. This depends on where you want shadow detail to emerge and how "black a black" you want in your image. The RGB values should be neutral or equal (example: R 20, G 20, B 20). This may sound complex, but it is not. Setting the black point according to these criteria will give you an amazing amount of control over shadow detail.
Please see the Black Point Setting section for more information.
Please be aware that even on a calibrated and profiled monitor the correct images will most likely look too light in the shadows. You must remember that we are adjusting these images for ink-jet output, not monitor output. Most monitors can display more shadow detail than ink-jet printers can replicate.
The following images compare correct and incorrect black point selection. The first pair compare the original image with one that has proper white and black point selection. The location of the image's black point selection site is circled in red.
Comparison of Original Image and Correct White and Black Point Selection
Original
Image Proper
White Point and Black Point Selection
Comparison of Correct and Incorrect Black Point Selection
The second pair of images both have proper white point selections. The image on the left has an appropriate black point selection. The image on the right's black point selection (circled in red) is too light an area. This improper selection forces all lower values to go completely black.
Proper White Point
and Black Point Selection Proper
White Point and Improper Black Point Selection
