We often use curves adjustment within the Image menu in Photoshop for changing the contrast of colors within the layers or image. This option is quite good to Enhance the overall contrast and the tonal range for getting a quick result in small time. Best part of this tool is that you can make changes to the bright portion of the image without disturbing the darker portion.
By overall enhancement Means that we can use this option either on the entire clipboard or on the marked selection manually within the specific layer.
Curves adjustment works basically over the color contrast, color and tone of the image pixels. So if the image have the dark colored pixels in the image, we can add more color to each pixel by choosing the samples and make the overall changes.
So if you are choosing to add more contrast or color tone within the image, then the curves option adds up RGB(white) color to the dark pixels of the image, and also for the facility given by the point sample option within the curves palette, and we gets the result according to the color gets enhanced.
Same goes with choosing to change the color tone to dark(adding black).
Within the curves palette there is a graph showing in the ascending order. It comprises of five points:
Black point (Black color)
Shadows point (Grey color with black dominating)
Midtone point (Middle portion)
Highlight point (Grey color with white dominating)
White point (White color)
Adding points upward in the garph add up more whiteness in the image, and adding points downward add up the black color.
For general purpose people often use the s rule, which means to make the graph look like s-shaped. This helps with the gradual change within the contrast of the overall image.
For making changes to the graph there are several tools within the curves palette, see below some of the changes made to an image which I have taken from here: http://wallpapersfor.me/tag/skyline/
From the above you can distinguish the differences within the images. Curves adjustments are really help full brighten the image or if you want to give it a specific tone like sepia or any other of your suit.
Alright that is all for now, I hope you liked the introduction of curves adjustment. thanks for reading it.
Have a nice day bye.