Show, don't tell 7 Oct 2006

Photoshop's "Hue / Saturation" dialog displays a series of sliders that allow users to tweak the hue, saturation, and lightness (luminance) of the reds, yellows, greens, cyans, blues and magentas in their images. When users drag the sliders to the left or right, Photoshop tells them the amount by which the colours have been altered - for example, "+18" or "-13". Ittells them, but it doesn't show them.

To use Photoshop effectively, you need to be able to take abstract values like "-13" and visualise the colour changes they imply. As these raw numbers are the only feedback provided, you must construct a picture of the new colours in your mind. Photoshop therefore assumes that your brain is capable of some pretty serious mental gymnastics - yet in reality, such cognitive dexterity is beyond the majority of us.

"The problem with the Photoshop control is that it requires you to use the logical parts of your brain when using it. You have to know that when you reduce the hue for the blues, that you're taking them to cyan. And when you increase the hue, you are moving them to magenta. This is all basic color theory. But you have to think too much about it with the wrong parts of your brain."

Contrast this with the approach taken by Aperture. Aperture's sliders are accompanied by visual cues that show users the effect of their changes. When you move a slider left of right, the small block of colour that appears alongside it is updated to reflect the associated reduction or increase in hue, saturation or luminance. Thus, Aperture shows users the amount by which colours have been altered, in addition to telling them. A far more effective solution.

"It's not just numbers and words mixed together in a way that makes the left side of your brain go into analytical mode. There are colors and icons there that speak to the right side of your brain—the same part that you're using to evaluate the image that you are looking at."