Can i use red/green text colors to provide additional information?

Question

I have an text outline tree where i display a lot of information There are already upto three icons for each item (one in front, one after the text and one at the left side). But i still need to show more.

So i used different text colors. Unfortunately only the red=stop,forbidden,protected and green=okay,valid,allowed is so universal known. I mix it with black/blue which stands for none available information items.

My question is: Do red/green blind people recognize the difference of this colored texts?
I don't really care about real color blind people as they are in the 0,001% range while red/green blindness is serious high in the one digit percent range.

EDIT: I heared from someone that he is red/green blind and is able to tell me if this is a green text or a red text and only if this is a real mixed color salad they are not able to differenciate between it. So the question is: are text items in a GUI list/tree so far away from each other that red/green blinded people can see them as different shades in whatever color they see.

Answer 1

Could you maybe use bold/not bold/<span style="color:silver">grayed out<span> instead? (Sorry couldn't make the text silver colored.)

Answer 2

I agree with a great deal of what you say.

Red and Green are a very recognizable combination in terms of meaning.

In terms of colour blindness, the shades of green and red differ greatly in how "bad" they are. If you want to make sure you have a usuable UI look at it in black and white. (I take a screenshot and give it 20 seconds in Photoshop.)

If you can use what you see, move on. Otherwise, address the problems.

Kindness,

Dan

Answer 3

Red/green alone is bad for this reason. My boss actually has red/green colorblindness, so he points out anytime we mess up and he can't distinguish something.

Consider an:

• outline box (eg dashed)
• Background color
• text bold/not bold
• Yet Another icon
• A variation or overlay on an existing icon
• A mouseover hint (title)

A mouseover is actually a generally useful thing - while an icon may be intuitive to you, it might not be to someone using your app for the first time.

I agree with the suggestion to make it black-and-white to try it out- though there's also a couple Firefox extensions that do this: https://addons.mozilla.org/en-US/firefox/search?q=colorblind&amp;cat=all -- unfortunately, none seem to be updated for 3.5.

Answer 4

NO, we do NOT see the difference! I worked at a company that used red/green for information regularly, and it was very confusing.

But, do as they do in traffic lights, and add a little blue to the green color. FF0000 and FF00CC is easy to tell apart (for me, at least).

Also, its eaisier to tell larger text/tings apart. Small pixels or pixel-thin lines are harder to see the color on.

Answer 5

7% of American men have some form of Red-Green color blindness. The rate among women is much lower. Incidence rates in other countries vary, but part of that is due to the low rate of diagnosis.

So, for the sake of ADA-compliance and conformance with UI best practices, don't use red and green colors alone as an indicator.

Also, no one wants to use an application that looks like angry fruit salad.

Answer 6

Colors may give cues, butthey should not be the only way to find that information.

Personal

I have a red/green deficiency, here are some of my experiences. Keep in mind color vision is very individual even among normal-sighted people. Some of that may be true in general.

• Telling colors apart is easier than identifying colors
• closeby large areas are easier to tell apart
• Trying to tell colors is strenuous, it's less of a cue, more of a task (i.e. color coded UI exhausts rather than helps me)
• I can tell RGB(255,255,0) from RGB(0,255,0) and ident when they are side-by-side, and can tell you "which is greener". However, I can't play most puzzle games that use these for color-coding pieces.
• Mixed colors give the most problems.
• An intern once asked me "are you gay or what", because the desktop background - some paintshop landscape - was all pink. I didn't know.

Imagine a list control (like an windows explorer file list) where file names are black, red or green:

• telling red apart from black is hard. I usually don't notice until someone tells me. Even on decent TFT's, from a slight angle they wash. I can identify correctly if someone tells me "some of these are red" and I look hard.
• I once deleted 3 days of work because I failed to list of files on the left was red not black (this was a font with 2 pixel line width!).
• having a single red or green items among black ones, it's hard to tell whether it's red or green.

People deal differently with defects, and though I've never found a color vision deficient person to be ashamed or hiding about it, we still don't like to have it rubbed in. Some people, incidentally, get very argumentative because they can't imagine I can tell apart X and Y easily, but not X and Z. My best way to quiet them is to ask them to explain the color "blue" without using any color names.

General thoughts

Well chosen colors make valuable cues, improving UI transparence immensely. Don't stop using them for good - just allow people who don't see them easily to still use your software.

Allow customization of colors, and provide color schemes to quick pickly. I really don't want to select 14 individual colors.

Using slightly-off colors often looks much more professional than the "primaries" (one or two channels at 255, the last at 0).

Color perception differes a lot. What looks good to you on your monitor might suck everywhere else.

First, there's color reproduction of the monitor - they have huge differences in linearity, balance and isotropy. Unless you use the same brand from the same batch, or use properly calibrated profesisonal monitors, they make for the biggest difference-.

Second, is your sensors. There's an about 40/60 distribution among people of red perceptors working at different wavelengths. There are many more subtle personal differences.

Third, it's your brain. A lot of color perception is learned and affected by cultural background. see e.g. here.