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High color, true color, bits per pixel, whatever you call it color settings can be confusing. I'll outline the differences.

What is the difference between high color and true color and which setting should I use?

Describing the difference will require that we look at how images and color are turned from a collection of nothing but numbers to actual colored pixels on your screen.

Which you should use, I'm afraid, depends on you. I'll give you some guidelines.

Colors From Numbers

As you probably know by now, your display is a rectangular array of dots called pixels. Your screen resolution is what determines how many pixels there are - a 1280x800 screen, for example, has just over a million pixels.

"For most people these days I think we tend to land on 24 bit color as the compromise."

Your computer controls the color of each pixel individually. Conceptually that's done by assigning a number to each pixel, and the graphics hardware does whatever graphics hardware does to turn that number into the colors you see on the screen.

The issue we're dealing with is this: how many colors?

Numbers of Colors

Fundamentally the difference between Medium, High and Highest, or High color and True Color is, to put it oddly, the number of numbers that can be used to represent the color information for one pixel.

Windows tends to use terms "Medium", "High" and "Highest" to represent the different alternatives, so I'll use that here:

Color Setting Bits per pixel # of different colors Memory for 1280x800 screen
Medium 16 65,536 2 megabytes
High 24 16,777,216 3 megabytes
Highest 32(*) 1,073,741,824 4 megabytes

(*) Since 32 cannot be evenly divided by three to represent separate red, green and blue color values, 32 bit color is typically actually 30 bit color.

Color Variations

Now, here's where things get ... interesting. Or confusing. Or just plain weird.

  • The visual difference between 16 bit color and 24 bit color is noticeable, but not horribly so. Photographs in 16 bit color suffer the most, but even "suffer" is perhaps too strong a term. You'll probably notice it in smooth gradients of color like the variations of blue in the sky. If you can see distinct shades of light blue across the sky stepping from one to another, that's likely the result of 16 bit color. On the other hand, if there are no photographs involved, and all you do is look at word processing documents all day - even those in color - you'd probably never notice, or care if you did.

  • Depending on the graphics hardware involved 32 bit graphics may be exactly the same visually as 24 bit. The difference in size is simply to take advantage of the fact that computers handle things in groups of 32 (4 bytes, a power of two) much faster than they do in groups of 24 (3 bytes, an odd grouping from a computer's perspective).

  • If your graphics hardware does indeed support true 32 bit (or, rather, 30 bit) color, you may never notice the difference between it and 24; particularly on the average computer monitor.

  • No matter what you do, the monitor or display plays an incredibly important role in how colors actually look, and how "true" they are. Without calibration the three identical monitors in front of me right now all show the same color ever-so-slightly different.

  • I've seen "True" color used to refer to either 24 or 32 bit settings. It follows that "High" could mean 16 or 24. Needless to say, pay attention to the bits-per-pixel; the 16, 24 or 32.

Your True Colors

So, which should you choose?

I can't say; it depends on you, your vision, your monitor, your computer, your graphics card and how you use your computer.

If you're a professional photographer and will take the time to properly calibrate a fairly high-end monitor then you'll probably want (true) 32 bit color.

If color depth isn't important to you - perhaps, as I said above, you work in a word processor all day long or never or rarely look at pictures in any real detail, then perhaps 16 bit color is plenty. It'll be a little faster, too, particularly on your older machine.

For most people these days I think we tend to land on 24 bit color as the compromise. Pictures look good without going overboard, and the sky doesn't have that "stair step" feel in its color gradient. If you know how your graphics hardware supports it, you might play with 32 bit as a speed enhancement, but in the long run it may not be worth it.

And finally, if you're running Windows 7 with the "Aero" interface - don't even look for the settings. Windows has chosen 32 bit color for you, however it's implemented, as it's required by the fancier graphical interface. Aero needs the speed.

Article C4694 - December 30, 2010 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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2 Comments
Ron
January 4, 2011 11:14 AM

I believe that 32-bit color is actually identical to 24-bit with the addition of an 8-bit alpha channel:

8-bit red
8-bit blue
8-bit green
8-bit alpha

The alpha channel sets the transparency of the displayed pixel

That's one version, yes. Sadly there are several variations on "32 bit color".
Leo
04-Jan-2011

Terry Hollett
January 5, 2011 6:17 AM

I think a lot of this are just marketing plies. That's like digital cameras. Some resolutions going up to 3000 or more. Who's print size would in some cases take up the side of a small house.

Pictures that mostly are sent in emails and posted on Facebook.

I have a picture on my computer now that is 3600 by 3176. It's print size is 40" by 35". If I reduced it to 800 by 600 I probably would not be able to tell the two apart, like most people.

It gets to a certain point that most people cannot tell one resolution from the other. Either monitors or camera pics. My opinion it's mostly marketing hype.

Like 3D TV. another story.

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