Brightness and Gamma Correction

It pains me to see many pictures of miniatures on this site getting low marks simply because the pictures are too dark, when this can be fixed very easily using any old photo editor. Hence I decided to write this short article.

First, let me try to explain what Brightness, Contrast, and Gamma are, and what happens when you change them.

Brightness is the average pixel value of all the pixels in a picture. When you increase this value it brings the value of every pixel up in a linear fashion. So the visual effect is a literally brighter picture. If you overdo it, the picture will have a washed appearance because the pixels that are supposed to be dark are now too light, and there is too little contrast between light and dark areas.

Increasing brightness just a little bit is a good way to lighten up those miniatures that look a little on the dark side. If the miniature is too dark however, this is not the best method (read on).

Contrast is the deviation of the pixels in a picture. If you increase contrast, the light areas will become lighter, and dark areas will become darker, keeping the average brightness the same.

I do not recommend playing with contrast much, since the details in the dark areas will be lost in the process. Also colors will begin to deviate from what they really are, and they will become brighter. (I'd almost consider it cheating to try and enhance an image in this way, since it begins to become computer art instead of miniature painting.)

Gamma correction is a nonlinear (exponential to be more precise) adjustment to brightness. It affects the brightness of the darker pixels only a little, where as dramatically increasing the brightness of the lighter pixels. What happens with most scanned images and digital images, is that the pixel values are translated on a linear scale. However, for the human eye, this often is a dark spectrum.

What this means to us miniature painters, is that using a degree of gamma correction will bring the picture to a more pleasing detail level for our eyes. The gamma value I recommend is something between 1.4 and 2.7. Where do I get these values? I base them off of the correction automatically applied by some digital cameras, scanners, and even display adaptors and computer software.

A few things to watch out for:

1. If you are using a Mac or a Silicon Graphics WS, the odds are you already have built in Gamma correction, and those dark pictures don't look dark at all for you. It's all the other pictures that look washed out in the lighter areas, or grainy in the darker areas. Keep in mind PC's don't use any built in corection.
2. If you have a Laptop, do not trust the picture you see on your LCD. It can be deceptive in many ways (color, brightness, etc). Use a regular monitor if you can.

To conclude I would like to give an example of what a few minutes with a photo editor can do for you. I was helping Steve Steine (thanks for letting me use these pictures) improve the picture of a converted Mangu (from Reaper), that he poured many hours over painting. I hope the adjustments give the miniature better justice.