Trying to photograph or duplicate someone’s artwork for reproduction can be tricky. First there is presentation. Then there is even lighting. There are also a number of post-production issues you have to figure into the mix before you are ready to print. One of these post production issues we all struggle with is white balance.
I have seen several YouTube(tm) videos showing a “Photoshop Trick” for white balancing .jpg files that have a color cast. After a lot of experimenting and some modification, this trick also seems to work when photographing artwork for reproduction. Artists are quite picky about getting the colors exact when reproducing their work.
Of course the best thing to do when photographing art for reproduction is to use a color patch card like a ColorChecker Classic(tm). But when your efforts fail, or you left your card on the shelf, I find this trick useful. The problem is, I only need to use this color balance workflow occasionally, and hitting the replay button on YouTube(tm) videos is getting old. So I thought I would list the workflow for easier reference. This post assumes you know your way around PhotoShop CC. If not, you can view a couple of the many videos on this subject here and here. Just one caveat, no workflow is perfect, but it is a start.
- start with the your base (background) image. I only do basic lens distortion correction in Adobe Camera Raw prior to bringing the image into PhotoShop. straighten and crop the image to the dimensions ratio you need.
- for this trick to work, the exposure needs to be essentially neutral. you don’t need to do all of your dynamic range correction yet but the main peak of your luminous histogram needs to be near the middle of the range. You can use a brightness/contrast adjustment layer for this.
- add a new layer above the background layer
- fill the layer with 50% gray by selecting edit : fill and select 50% gray in the dialog box.
- change the layer blending mode to “difference” (the colors will look funny)
- add a threshold layer above this 50% gray layer. set the threshold <= 10 (some people will go as far as <= 25); until there are just a few black areas over your image. these are the areas closest to 50% gray. if there are no usable black spots at a threshold of 10, you need to reshoot (havn’t been that far off yet).
- zoom to 100% in the image and using the color sampler tool mark one of the black areas by clicking the mouse button whiling hovering over the area.
- while still zoomed in, turn off the 50% gray layer and threshold layer.
- add a curves adjustment layer anywhere above the background layer
- grab the middle gray dropper from the curves adjustment dialog box and click EXACTLY on the mark you left with the color sampler tool.
The image I used (thank you Laura Pendergrass for the use of your image) is not one of my art reproduction images. Usually art reproduction images have a narrower dynamic range (luminous histogram) so further tweaks might include trimming the white and black ends of the dynamic range with a levels adjustment layer. If I am going to print the image right away I add another levels layer and move the contrast a little to the left (1.05-1.15) to correct for monitor brightness. Others might get the same result using either a brightness/contrast or curves adjustment layer. Since the goal here is accuracy in reproduction, “eyeballing” color correction usually doesn’t work. Client/artists usually don’t want the colors of their work changed, even if we can make them “better”. From here, all there is left to do is save, flatten, size, sharpen and print.