Images 3 - Enhancement Video 9 min
Core images may be expressed in HSL format (Hue, Saturation & Lightness). Lightness, as the term implies, is the major control of how dark or light the image appears. It is valued from 0 (black) to 255 (white) for each pixel in the image.
CODD has 3 different ways to change the Lightness and/or contrast of the active (top) core image within the function Change_Lightness. Open a core image plot, run the function, and select from:
DC Offset - the image is lightened or darkened by a set amount. Does not affect contrast.
Multiplier - the image lightness values are multiplied by an input constant. The histogram of values is stretched and contrast is enhanced. Greater input number will produce greater contrast.
Histogram Stretch - automatically stretches the histogram of values to span the entire range of 0 - 255.
Batch_Change_Lightness will apply lightness changes to all of the images within a selected image folder.
In practice we usually run Change_Lightness on a single core until we are happy with the result. We then run the Batch function for all of the images from the hole.
The process acts on the active (top) core image.