Each image has its history
The historigram is one of PhotoShop‘ windows that contains more information, and usually one of the most unknown.
Taking a look at historigram panel you can get information about dominant lights, if the image has been previously retouched and, if properly corrected and enlightened, etc … Also it will helps you to have abetter understanding of the image that you are working.
Without going into all of its functions or details I will show you, for all those who do not you use it frequently, how to configure it to be useful for correcting images.
First of all you must use the all channels view and set the upper historigram to show you the information of brightness throughout the image, the luminosity channel. As historigram’s panel take too much space you can change between show/hide when it is needed. Please note that historigram shows the entire image if you do not do any selection. So you can select any range with your mouse by clicking into its historigram panel.
- But what historigram shows you it is the amount of color per level, measured in pixels with 256 levels of brightness stacked on the same coordinate axis X. Right (255, highlights) to left (0, shadows). If you have any questions about how this works try to duplicate the image and to change its mode to screen, you will see that all the color channels extend into the highlights, while if you put it in multiply mode it falls into the shadows.
- In regard to the neutralization images, unless you have very large dominant light as in outdoor areas, sea, colorful fruit, when an image is well corrected, RGB will have a balance in all channels. In CMYK magenta and yellow channels should be balanced with a preponderance of cyan.
- An ideal situation would be that for each channel historigram went from shadows to highlights without going to saturate the whole (when the account reaches the top of historigram) at any level, this implies a rich in tonal ranges and consistently illuminated image. Of course this is a standard that must be known, but not always be reached. If you want very contrasted images, shocking and very artistic, the historigram should be complete opposite of the ideal situation.