More Answers about the new iPad and Color

iPad2 gamut over iPad3 gamut

Please see the previous articles in this series:

Color Management and the iPad

Questions about the new iPad and Color

Answers about the new iPad and Color

The graph above compares the color gamut of earlier iPads to the new iPad. The difference is quite apparent. Ever since the days of the early color screen iPods, Apple’s iTunes app has been doing color conversion before creating down sampled images for sending to what are now called iOS devices. This could be tested by tagging the same image with a larger and a smaller color space, while not changing the actual image colors. If iTunes was ignoring incoming color profiles, the images would be identical on the iOS device. If images were being converted, then they would end up being different, as they would be converted from different source spaces. The latter was true, showing that images were converted on the way to the device. But converted to what? We jokingly called it iPodRGB, then later iPhoneRGB, and later still iPadRGB.

Now that Apple has created its first iOS device with a noticeably different color gamut, are they converting files differentially for the different device gamuts? Certainly they are creating different file sizes and resolution for different devices; the same file is larger, when rendered through iTunes to a new iPad, then it is when rendered to an earlier iPad. But more to our point: the color is different as well. E-mailing the same image “back to the Mac” from the new and an older iPad results in versions which are both different in size, and different in color. Resizing them to an approximate match, and overlaying them in an animated GIF results in the image below.

The same image, returned from older and new iPads

I apologize for the blinking image, but it is the most efficient way to show the changes. “What changes?” you may ask. And its true: the number flashes from 2 (older iPad) to 3 (new iPad) and the grid move a pixel or two, but the colors really don’t seem any different. In order to produce an animated image, its necessary to use the GIF format, which offers lower color bit depth than newer format. So for the most part, the minor differences in color are lost. But even in Photoshop at full color depth, the difference tended to be indistinguishable to the eye. However the RGB values of many patches were as much as several points different. So this may not be as big a deal as the headline “Images sent to New iPad are Color Converted Differently” could make it seem.

In a practical sense, how does this matter to the end user who cares about color? The same way it did in the past: Apple’s secret iTunes conversion to unknown colorspaces for iOS devices was apparent to those serious about color long ago, and has not really changed. Sending the same image to any iOS device through iTunes does not end up with the same result as emailing the image, or otherwise transporting it to the iPad outside of the iTunes process. Images imported outside of iTunes are not downsampled to what Apple considers an optimal level, so your iPad may get full much faster. And then there is Apple’s unmentioned color conversion. But now, there are multiple, slightly different, iTunes color conversions; the plot, as they say, thickens.

Apple is attempting to make this all invisible and automatic, to simplify the end user experience. Those with more advanced needs are left to deal with these simplifications as best they can. The first conclusion you can draw is that importing images through iTunes to your iOS devices, then sending them on for other uses is not a good idea. Images you wish to have retain known colors should be emailed or otherwise sent to the device instead. On the other hand images in color spaces other than sRGB, such as AdobeRGB, will be more appropriate if converted though iTunes, though the best solution is to convert such images to sRGB before outputting them to any mobile or web usage. A further conclusion is that those concerned about color should use the consistent method of their choice for importing files to their iOS device, and avoid mixing and matching files from iTunes and other sources. And the final observation would be that using SpyderGallery for color managed display is still the best choice for controlled iOS color.

Credits: C. David Tobie, Copyright 2012. Website: CDTobie.com Return to Blog’s Main Page

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10 responses to “More Answers about the new iPad and Color

  1. Pingback: Answers about the new iPad and Color | CDTobie's Photo Blog

  2. Thanks for the great info. I am a bit confused on the best way to store and manage images on my new iPad. I would like to use the spydergallery to display images for clients and if I make a sale I want the ability to transfer the full res image files from the iPad directly to the customer or their printing provider. I have found an app called ‘fileapp pro’ which allows transfer of full res image files (edited on my spyder 3 calibrated monitor) and it maintains all file naming and associated file info, including the Adobe RGB color space. This app has its own file / folder ‘browser’ as well as an image viewer built in (but when used on 24MP images it is quite sluggish). And of course there is no color correction using this viewer.

    So I’ve solved the problem of importing, storing, orginizing and outputting original images with Adobe RGB color space. My question is: How do you recommend I ‘convert’ these same image files for viewing in the spydergallery app? The ‘screen shot’ method may work for getting them into the camera roll but with 100’s of images and no file naming once in the camera roll it would be very difficult to find the matching full res files for output to the customer…..

    Any ideas or suggestions would be very much appreciated.

    • You are certainly pushing the envelope putting full res files on the iPad, and distributing them from there. Since you want those files in a larger gamut than sRGB, you will need a segregated solution to view them correctly as well as store them for forwarding. That will mean importing them twice; once in high res AdobeRGB for forwarding, and once downsampled and converted to sRGB for viewing on the iPad. This will eliminate the lag, since you will view the smaller files. but it will mean more housekeeping, to deal with two sets of files.

  3. I am currently in the finishing stages of a new fixed-layout image-heavy ebook for iBooks. I have an first-generation iPad, and on that, I’m considering final conversion of images (currently sRGB) to iPad.icc . But I’m wondering if I may create more problems when viewing on a New iPad. (Boy, will that name get old!)

    Do you have any solid info or well-educated guesses as to this, and to iBooks’s handling of embedded profiles?

    Thanks.

    • I am about to do some iBook testing, to see what sort of conversions it may invisibly make (similar to iTunes). As for converting for the iPad 1 & 2 colorspace; that will be rather self defeating, given the nearer-to-sRGB color space of the new iPad, which is moving towards representing 10% of the iPads out there already, and will be a much larger percentage before too long. Datacolor plans to offer an SDK to other developers to allow color correction to the SpyderGallery profile in apps other than Gallery, but that isn’t ready yet, and in any case won’t help with iBooks, as that would require Apple to institute our SDK, and I really don’t expect that to happen…

  4. I think there is more to the issue than just gamut. For instance, if I convert the print book’s GRACoL6 color to iPad.icc in Photoshop, and use the resulting hex code in my CSS, the results (very much so on blues and reds) are MUCH closer to the original, both in hue and luminosity.

    It was tht recent test that prompted me to consider a late-stage conversion of images, and I probably will duplicate the book and convert the images for one of them, load both, and compare the results myself.

    I don’t have an iPad 3 for comparitive testing, though.

    • I agree there is more than gamut involved; there is also the twisted primaries of the earlier iPads. And wr have great luck fixing that with a profile conversion in SpyderGallery. But my point still stands; If you fix it for the earlier iPads, you will be sure to bust it for the new ones. Take your pick; but without device calibration it’s hard to have it both ways. You could perhaps publish two editions of your book, one for the iPad 1 and 2, and another for the iPad 3, each with differently converted images. That would be about the only fix I could suggest.

      • Thanks for your reply, David. So then I’m probably best in the long run sticking with sRGB-targeted images (though I’ll still use the iPad.icc-calculated text colors because they look too light and saturated on the iPad 1, and if they are brought darker by the iPad 3, that’s not as much of a problem — and they don’t need to match other elements). I look forward to your iBooks test results, and a clear call on whether iBooks (which is essentially Webkit lite) is honoring, ignoring, or mangling embedded RGB profiles.

        I will cross-post, but I encourage you to publicize your results on Twitter using the #eprdctn hashtag. There are a host of technically strong ebook developers using that very active hashtag.

  5. Pingback: iBooks Author – Image compression | Davide Barranca

  6. Pingback: iBooks Author – Compressione delle immagini | Davide Barranca

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