The Importance of Color Accuracy

Contrast Ratio: It’s Not Everything

When it comes to picture quality, brightness and contrast ratio are often talked about. However, we want you to realize that the most important element is neither contrast ratio nor brightness, but color accuracy. It’s true that we want contrasty images that aren’t washed out, but when we use the term “contrasty,” we’re actually talking more about micro-contrast and color accuracy than actual contrast. To prove this to you, let’s see why contrast ratio alone isn’t a useful measurement.

“Contrast ratio” is measured by comparing the intensity of the brightest white and the darkest black. Let’s take a look at two images

Is this photo sharper than...

...this one?

The top has a higher contrast ratio and obviously looks better. What’s important to notice is that your brain isn’t simply thinking of the second image as having less contrast, but is seeing it as being blurrier and less sharp. There’s actually no difference in resolving power, but that’s not how our brain interprets things. That’s why looking at test patterns alone won’t be effective.

That first set of images shouldn’t surprise anyone too much, but let’s take a look at another set of images:

Guess which has the higher contrast ratio?

It is this one

Which one looks more contrasty and less washed out? The second image is “less contrasty” and more washed out, but surprisingly, the contrast ratio in the washed out images is higher. There is a greater difference between the darkest black and brightest white in the washed out images than the nicer looking images. The problem is that contrast ratio only talks about the extremes of brightness and doesn’t say anything about the colors “in-between black and white.” That’s why looking at contrast ratio alone is misleading.

That’s not the only problem with contrast. Let’s look at these two images:

This could use a little extra contrast...

...but this is too much

Clearly the first picture looks better, but in this case, it’s not about the second image being “washed out.” The second image has a higher contrast because the difference in intensity between the clouds and the sky is greater. Still, it looks worse.

What’s really important is a concept related to local contrast and “microcontrast” which describes the local transition between the light and dark. It’s not that you want a big “overall” difference between dark and light portions of the image. You want the transitions between light and dark to be rapid and visible. In order for the clouds to look perfect, you want to see all of the texture rather than have all the colors be the same. You want to be able to see the fine differences in color. Micro-contrast is what gives images that 3-dimensional, looking-through-a-glass-window effect. You want to see the difference between the light blue and the slightly lighter blue.