I hope this is as easy a question to answer as it is to ask…here goes…How do I know if I have perfect contrast…how does white balancing fit in here, if at all. thanks
One approach (the simplistic one) would be: "if it looks good it is good"
Now the scientific one: Open the Levels dialogue (or create a Levels adjustment layer) Observe the histogram. The extreme left of the graph is black, the extreme right is white. Assuming your subject contains both, the histogram should span the full width.
If it doesn’t, drag the sliders in until they meet the extremities of the histogram. In theory this should give you correct contrast.
I say "in theory" because correct is subjective.
This is where judgment comes in. Observe your image and decide which areas ‘should’ be black and which ‘should’ be white. By this I mean the deepest shadows which should contain detail and the lightest areas which should just contain detail. (Specular highlights, for instance, will not, nor should not, contain detail.
Now; hold down the Alt key and grab the left hand slider. The image will go white. Drag the slider until the areas you deemed should be the deepest black just start to appear as black. Then back off a fraction.
Do the same with the right hand slider. The image will go Black. Drag the slider until these area just turn white. Then back off a fraction.
You have now set the contrast. The centre slider can now be adjusted to set the mid tones to give a natural result.
In simple terms you could think of the outer two as being the Contrast adjustment and the centre slider as Brightness.
As for white balance. If you have something in the image which is known to be neutral grey, select the middle eyedropper (of the three in the Levels dialogue) and click it on the grey – before making the contrast adjustments above.
If you’ve no neutral grey and the colour balance is out, you can get it pretty close by doing the contrast adjustment steps above to each of the Red, Green and Blue channels in turn.
As for the brightness and contrast sliders in the Image>Adjustments menu – just ignore them. They are a remnant of the days before Levels and Curves came along to do a much better job.
Hope this helps.
Chris.
Thats good advice for RGB images – for CMYK your histograms should be slightly weighted – because typically you dont want to print a maximum black of 400%
Thank you both, the answers have been very helpful…L
In PS I changed mode from RGB to CMYK to make color corrections. Can I now change back to RGB as I have printing profiles for that were made for Adobe RGB 1998 working space? thanks, Mikey
If you ALT + Click drag on the sliders the display will show out of gamut regions.
eg where some regions will tend to white or black depending upon which slider is being ALT + Click + dragged
If you ALT + Click drag on the sliders the display will show out of gamut regions
….nobody ever reads post #1 !!
…nobody ever reads post #1 !!
nothing exciting ever happens there anyway… 🙂
As I mentioned in a different thread, "I also like knowing I can trash the prefs at my discretion and no one will think less of me, that there are least three ways of doing anything in Photoshop and that you guys will tell me ten of them, and that I never, ever have to read the first post. :)"
In CS2, the RAW converter has an option to see blown out highlights and blocked shadows all the time. The check boxes are on the top of the RAW dialogue, burn-out shows red and blocked shadows show blue. Neat!!!
