How good is your color?

There’s a bit of a hubbub about the colors on Apple laptops. It seems they’ve been claiming to display millions of colors, but the LCD displays only support 8 bits of color. There has been a lot of talk about technical means to tell how good your color is, but none of these get at the core issue: can you tell the difference?

So here are a few pictures which can help you determine the visible quality of your display.

24-bit color test

Look at the 24-bit image first. If the colors look like a perfectly smooth gradation, you have a 24-bit display. If you see bands the size of the black bars, then your vision is better than a normal human’s. (Or so the conventional wisdom says.) If you see bands that are significantly wider than the black bars, then you probably have an 18-bit display, like the ones Apple apparently is using.

On 18-bit displays (6 bits each for red, green, and blue) the 24-bit color bands should look like the ones in the 18-bit test image. This is equivalent to the “thousands of colors” mode on Mac OS 9.

In case the color bands aren’t obvious in that image– which is typical in bright daylight and other adverse situations– here’s a 4-bit test image. Which brings up an important point: if you couldn’t see the color bands in the 18-bit image, you might want to turn out all the lights. Don’t do it right now, though, the after-images in your retina from looking at all these vertical lines will make you see bands where there aren’t any. That’s why I had you look at the 24-bit image first.

I haven’t tested this on any laptops yet, so it will be interesting to see what other people report. I can verify that my generic desktop 19-inch LCD is fully 24-bit. (I’m slightly red/green color blind, but that doesn’t matter for this test.)

So how did Apple come to be in the position of advertising 24-bit, but delivering 18-bit? This is pure speculation on my part, but here we go. Traditionally, laptop displays have been significantly worse than desktop displays. Desktops had bright cathode ray tubes (CRTs), while laptops had the most state-of-the-art liquid cristal displays (LCDs). State-of-the-art originally meant you could see beige-on-black, unless you were to one side, in which case you saw black-on-beige. Over the years LCDs have improved from awful to not so bad. My 7-year-old PowerBook has a slight greenish tinge, which you don’t notice unless it’s next to a better display. You wouldn’t notice the difference between 24-bit and 18-bit very easily on that.

It used to be that the video cards were the limiting factor in the color display, so once 24-bit cards became cheap, Apple started to discourage the use of the 18-bit color mode. From there, it became easy to forget that the laptop displays were still only 18-bit.

Assuming it really is 18-bit. Again, I haven’t tested it, but there are ways to cheat. Dithering across pixels (or sub-pixel, as some have suggested) won’t help in this case, but they could dither across time: you can cheat by flashing between two nearly-identical colors. If the LCD refresh is slow enough, the liquid crystal might actually remain between those colors– producing a real intermediate color. I’m skeptical that Apple would do this, since the LCD manufacturer has more interest in investing in these sorts of tricks, and I would suspect that true 8-bit-per-subpixel quality is easier for them to get at directly.

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41 thoughts on “How good is your color?

  1. I have a macbook core duo (one of the first, ordered right after they shipped) and my color is beautiful. No lines are visible on the 24bit image. BUT my wife shortly after purchased one because we loved mine so much. It’s screen was just as crisp and beautiful. Was until the macbook died and they repaired a part that Apple techs couldn’t identify by the part #. When we got it back boy was that screen grainy. I could tell (because I am a graphic designer and know what it looks like) that it was no longer rendering the proper bit depth. We got it replaced by a new macbook out of the box same issue. I was told that I was being too picky.

  2. I can’t see the banding on my Macbook Pro when the image is embedded in your web page.

    However if I open the file up in Photoshop, – I can see the banding when zoomed in.

    eg RGB 225:0:0 to 223:0:0 is the same color.

    There are other problems with your test image:
    If you zoom in, you can see that you do not have vertical lines of color, – use the dropper tool in photoshop, – you can see that the lines jump back left and right a few pixels as you go down the page.

    It’s a shame daringfireball.net has linked to your post, – I don’t think what you are asserting is correct, and I don’t think your test images are up to scratch.

  3. Thanks to Daring Fireball for sending a link over. I just got in a MacBook Pro yesterday. I was curious to see what would be up with the monitor.

    My new 17″ MBP would appear to display the 24 bit color pattern perfectly.

  4. Just checked on my first-gen Mac Book Pro 17″ and the 24-bit images shows no sign of banding…

  5. I have a June 2006 MacbookPro – original CoreDuo @ 2GHz. I’ve been following the brouhaha over the screen color depth over the last couple of days, and so was eager to take a closer look at my screen. I do some amateur web development, including some design work (I used to be a designer, but now am a CS grad student).

    I was very happy to see a big difference in between the 18-bit and 24-bit images, with the 24 bit one being very smooth, the 18-bit one obviously noticeably stepped. So I can safely say I believe my screen to be a full 24-bit 16.7 million color screen.

    Can’t speak for anyone else though.

  6. On my 15″ MacBook Pro (core 2 duo) I see the bands on the 18-bit image but the 24-bit image looks smooth

  7. I’ve looked at the 24-bit test image on my MacBook Pro core duo and cannot see any bars like the ones that appear in the 18-bit test image … what am I to make of that? It may not technically be a 24-bit display, but what is the saying? … if it walks like a duck and quacks like a duck?

  8. Hmm… On my first generation MacBook Pro the 24-bit picture looks completely smooth while the 18-bit is definitely banded like you described it. Does that sound right? Isn’t this whole class action thing meant to be about this model only being 18-bit? Maybe it’s my eyes…

  9. I see no bands on the 24-bit test image on my 15″ C2D MBP (ordered in October last year on the day they were released).

    I can clearly see the banding on the 18-bit test image.

  10. On my MacBook Pro (Core Duo), I can’t see any banding at all in the 24-bit image. There is a bit of crawling if I move the window around, and I see some banding then. It sure doesn’t look like the 18-bit image, where the banding is clear and obvious.

  11. On my 17″ MBP, (real recent.. 2.33 x 2gig x 160), I see NO banding on the 24 bit test, and bands matching the black bars on the 18bit and 4bit images..

    Does that just mean that my aging eyes can’t see what should be there?

  12. Hi there,

    I have created the website http://www.colorblindmac.com after finding out that my LCD screen built in my MacBook Pro was only 6-bit.

    Have a look at this http://peewaiweb.free.fr/#howcanibesosureofthat to check your screen, there is a link to a program that dynamically generates a picture to check your gradient.
    Using it, you eliminate the risk of artifacts produced by the compression of web images. And you also avoid any dithering at the rendering engine level.

    There is also a forum on this website to discuss the matter with other affected people.

    OTOH, some screens are way better than others, and it appears that the MacBook Pro matte are the worst ones.
    I am glad for you to know you re lucky enough to have a good screen and you don’t notice the banding!

    Just my 2 cents, cheers

  13. The issue is that Apple advertise their products as displaying millions of colors, when in fact they are using an 18 bit display, and cant produce nearly that many. The reason for using an 18 bit display is that it has better performance in other areas instead. I dont think Apple choose to perform temporal dithering on the display, they choose a display that does.

    However, my suspicion is that the problem here is not 18 bit displays. Something else is going on. My iMac screen looks very grainy when used in OS X ( very noticable, I saw it immediately ) but I havent noticed it in windows.

    The tech note for iMacs claims that 17″ iMacs are 18 bit, while the larger ones are 24 bit ( mine is 20″ ), so it seems like the graininess is not an articfact of the native display depth.

    I have calibrated my screen ( using the built in calibrater ) and I will see what it looks like with the default profile instead.

  14. Here’s a data point: my 17″ matte MacBook Pro (the latest, October ’06 model) seems to display the 24-bit image smoothly with no visible bands.

  15. Thanks for making these images – very useful. Couple of small errors in your text though. “… but the LCD displays only support 8 bits of color…”. In fact the problem is that some displays only support 6 bits per color component (18 bits altogether) maybe you just meant to type ’18’ as it’s correct in the rest of the article. The other thing is that 18 bits is not equivalent to “thousands of colours” on Mac OS 9 and earlier – in fact it’s still a bit better than that. (Literally a bit better – one bit per colour component, 6 bits instead of 5). 18 bits gives you 262,144 colours. The ‘Thousands’ mode on Mac OS 9 has only 15 bits or 32,768 colours.

  16. checking that on my just-outmoded MacBook Core 2 Duo shows that I’ve got a 24-bit screen.

  17. I have tried the three images on a MacBook Pro Core 2 Duo. I can see the banding on the 4-bit and 18-bit but the 24-bit looks as smooth as silk..no banding at all. This is in a darkened room.

    When I Google my panel identifier, it tells me that I have an B154PW01 V0 which is supposed to be 6-bit.

    Something clever is going on. Either Apple has an 8-bit version of the panel or there are some other tricks.

  18. On my core 2 duo 15″ macbook pro, the 18-bit images show bands, the 24-bit images look smooth.

  19. Pingback: 24 bit vs 18 bit screen - MacNN Forums

  20. Ok, maybe I’m missing something here. I checked out your handy 24/18/4 charts at work on my Dell workstation, which definitely has 24 bit color; the 24 bit image looks smoothly gradated..the 18 bit one looks banded..the 4 bit one..really banded.

    Now I’m at home on my 1st gen MacBook..and the images look the same as they did at work. In other words..the 24 bit one looks smoothly gradated…the 18 one looks banded..and the 4 one looks..really banded. I’m guessing by your writeup that the 24 bit one and the 18 bit one should look identical on my MacBook screen? Or..am i missing something here? 😉

  21. I just purchased a 2.16 Ghz MacBook Pro (15″) a week ago. So I don’t know if this will be true of the majority of laptop owners, but when I view the 18-bit test image, I can clearly see the banding. When I look at the 24-bit test image, I cannot see any banding.

    I then tried the test images on my older 20″ iMac G5. To the best of my knowledge, this screen is known to be 24-bit. Holding the MacBook side-by-side with the iMac, I can see no difference in the 24-bit image.

    Based on this, I think the laptop displays actually are 24-bit.

  22. I was linked to this page from LowEndMac.com – where they said “Odd thing is, notebooks have been using 18-bit LCDs for ages, yet nobody complained until now.” Correct me if I am wrong, but the 24-bit image should look like the 18-bit image if one’s display is only capable of 18-bit color, correct? Which would mean this last-revision PowerBook G4 I’m working on would have an 18-bit display (as lowendmac claims), and shouldn’t be able to smoothly display the 24-bit image.

    Unless my vision is extremely poor (which it isn’t), it does appear that Apple is using unusually low-depth displays in their latest laptops. If I’m reading these images wrong, though, please let me know.

  23. I have a MacBook Pro (aka. 18bpp display). I cannot see banding on the 24-bit image like the 18-bit image has. At full brightness I can see some banding effect in the darkest part of the image when I look really closely. I don’t know what the dithering method Apple uses is but it’s clearly good enough to fool me.

    Just in case it’s significant… I use the sRGB IEC61966-2.1 colour profile (see http://blogs.smugmug.com/don/2007/02/14/this-is-your-mac-on-drugs/)

  24. I stared quite long and hard at the samples on my Core Duo Macbook, which the widely advertised methods showed me to have a 6-bit display. “Thousands of coulours” yielded visible dithering in _both_ the 8 and 6 bit samples (this might be a color setting problem, the 6-bit sample should probably not have shown any dithering), whereas “Millions of coulours” did not show any visible artifacts. To me that is, there might be eagles out there who can find dithering, I wear glasses and don’t. So: I am still unsure if I have a 6 or 8 bit display but am sure that this is below my quality threshold.

  25. i really wanted an apple for the stability of the os, the included apps, etc, but decided to go with a lenovo/thinkpad instead becasue it’s the only laptop on the market of which i am aware where you can get an ips display. ips has great color reproduction characteristics. i’ve calibrated, and looked at the test images, and with this display i am easily able to seed the banding. when zooming into the images, i can also easily tell the color values apart, ie, there is a difference between r127 and r128. (as a side note, the images that leppik posted when zoomed in show goofy splotches, ie, the bands are not eve). to further test the color capability of this monitor, i created a blank image where one half of the image was pur red 127 and the other half was pure 128, then i asked my wife to tell me where the split was in the image. it’s tricky, but after looking at it closely, she was able to accuratley identify the split and the two different tones. ips is the way to go for color critical. wonder why apple does not offer that as an option?

  26. The vast majority of LCD displays are 18 bit. They use dithering to simulate 24 bit colour. I can’t comment on the grainyness that some users experience, but your basic 18 bit display can definitely reproduce more than a few hundred thousand colours.

    My ibook has an 18 bit display, but I find its colours look just fine.

  27. My reason for purchasing the macbook pro was to do photographic editing on the go while not connected to an external monitor.

    I know laptop companies choose to use cheaper screens to cut costs but I didn’t think Apple would do this also. My assumption for the cost of the macbook pro was the quality of the hardware. Guess I should look elsewhere.

    Thanks for the info.

    Oh this site is really good…helps with extra info. Everyone should run the application and see what model the lcd really is on your macbook.
    http://www.colorblindmac.com/

  28. FWIW: I couldn’t see it until I ‘zoomed in’ using Control-ScrollWheel hardward zooming.

    Banding is clearly visible only thereafter on my MacBook Pro while it is NOT visible on my Dell 2405 (which I assume, then, is a 24bit display) wile zoomed at the same level.

  29. I have a Samsung 226CW. It is a 6 bit display.

    There is no banding in the “24 bit” image, and it looks clearly better than the 18 bit image.

    Conclusion? When your panel is capable of a legit 5 ms response time (up to 2ms with over drive), temporal dithering works fine to prevent banding.

    The primary flaw of TN panels is that their color shifts to yellow at relatively small angles. When they quote a 160 degree angular range, that means the contrast drops to 10% at 160 degrees. I don’t care what my monitor does at 160 degrees, I care what it does at ~30 to 50 degrees, and at the moment TN just doesn’t work as well as i’d like.

    Nonetheless, I can’t afford IPS so its a moot point. TN is ok by me.

  30. Brand new 2.4GHz Core Duo MacBook, and although the 24 bit test image looks ok, there is a lot of background noise to the image, due to temporal dithering. Worse still, the grey background on the comments section shows a clear dithering pattern, something like a grid of dots. Nasty, and not what I come to expect from Apple, especially considering the price of a similar spec PC laptop.

  31. For those of you who have talked about how the 24-bit test image looks zoomed in, you’re missing the point! Depending on the software you use to view the image, you’re obviously going to either get banding (with simple zoom) or graininess (with dithering).

    I must agree with jim (second post) regarding the quality of your test image, though. You don’t have vertical lines of exactly the same color. There appears to be some kind of dithering going on in the original image apart from any zooming method.

  32. For me on the 20 inch aluminum imac; the issue is not colors; but the glare related to the glass glossy screen. Never had any glare issue with the matte display. What was Apple thinking by going glossy?

  33. Ooo. Thanks to this blog post I just figured out why my display was showing banding in the blue and red spectrums. I had the settings wrong on my T61p. Thank you!

  34. Running some older technology here… My 2006 Powerbook G4 seems to be running 24 bit. I see the bars on the 18 and the 4 though!

  35. I downloaded the 24bit image to my 16bit 240×320 Mio 168..
    In the microsoft picture viewer it just looks horrible. The green bands look exactly like the 18bit image(due to the green channel having 6 bits), and the 5-bit reds and blues are even worse.

    But brace yourselves people, in Resco photo viewer with dithering enabled, they all look great!
    if I look closely I can see dithering artefacts, but I think they would be a lot harder to see on a newer device with higher resolution.

  36. I don’t particularly like the picture on either my old PowerBook or my iMac 17″ C2D. The 17″ is brighter, but no color looks “clean”. The display looks like it has some sort of color noise, and i can notice slight flicker or pulsing. I want a calm picture! Probably something to do with fluorescent (mercury) backlight. I’ve never liked fluorescent light. Wolfram FTW. A screen with pixels that were totally static (when they’re not supposed to be changing of course) would be nice. OLED sounds great, as it did 7 years ago, now where are they? They said it was easier to make too. I don’t care if they last only 3 years, if they were cheap enough! Fix the longevity later. I remember reading about mirasol a few years ago. Seemed very interesting, but maybe very expensive for large displays, and seemed dependent on an external light source.

    Your 24-bit image didn’t have straight lines, as someone else mentioned. Zoomed in and could tell the difference on Green 59, 5A, 5B and 5C, so i’m guessing my iMac could be showing 8 bits per channel, by using some trick to make it seem so. 8-bit (24-bit RGB) really isn’t enough if you want completely smooth gradients. maybe 10 bits per channel would be enough?

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