Color Analysis of the iPad Mini and Retina iPad Mini

Note: I am republishing this article, as it pertains equally to the new Retina Display iPad Mini, which shares similar screen color with the non-Retina version.

Characteristics of the Fourth Generation iPad with Retina Display

There are not too many surprises with the fourth generation full size iPad (wouldn’t it be great if Apple gave these products functional names?). Its largely a refresh for the sake of updating the processor and moving the connector system to the new Lightning Connector. Both worthwhile improvements, but not anything to concern us here. Still, there are more questions to be considered with the new iPad mini.

Characteristics of the iPad mini

The screen of the iPad mini offers the pixel-count of the pre-Retina iPads, in a smaller form factor. Not retina resolution, but somewhere in between the non-Retina full size iPads, and the Retina versions, by way of its decreased screen size. Many will choose to live with this enhanced, but not “Retinaed” resolution (yes, I just turned Retina into a verb) in return for the convenience of the smaller form factor and the lower price of the new mini. But what about its color characteristics for serious uses? Has Apple taken a step backwards there as well, in order to make the new mini more cost competitive in its (already populated) size range?

Earlier Testing

The answer is yes, and no. As we know from previous testing, the Retina iPad screens (and the iPhone 5 Retina screen as well) have been updated from the earlier, twisted, sub-sRGB color space of early iOS devices, to a color space very close to sRGB. The gamut plot below shows the iPad 3, with sRGB overlaid, as that order provides the clearest indication of their match.  The green primary of the iPad 3 actually exceeds sRGB by a bit, but overall this is a great match.

sRGB gamut over iPad3 gamut

We have also studied the gamut of earlier iOS devices, and seen how this gamut effects their display of web images (in sRGB) and web videos in Rec-709, which shares a number of key characteristics with sRGB. The image below is the second generation iPad, overlaid on the third generation iPad, showing the smaller and twisted gamut of the earlier screens. There is no doubt that the color accuracy of the sRGB-sized recent devices is superior to the older devices.

iPad2 gamut over iPad3 gamut

Color of the iPad mini

With that background information in mind, lets look at the gamut of the iPad mini in relation to sRGB. First, its important to note that the white point (global color tone) of the iPad mini is close to the target value of 6500K, and the gamma (ramp from black to white) is very close to the target value of Gamma 2.2. In the image below, you will recognize the earlier, sub-sRGB gamut, and twisted primaries, with the added twist of primary green, and well as primary blue, being offset sufficiently from the sRGB primaries to lie outside of sRGB, making color correction that much more difficult.

iPad mini gamut in blue, compared to sRGB in red

Conclusion

Yes, this gamut looks quite familiar, as you can see by comparing it to the previous illustrations. The iPad mini does indeed revert to the smaller, twisted shape of the earlier iOS gamut. Apple seldom takes a step backward in their relentless move forward, but here we have one example of it. So, if you were considering getting an iPad mini for use as a photo or video portfolio, please note that these color deficiencies will effect your results.

It is quite likely that in the next generation of iPad mini, Apple will move the device forward to a full sRGB gamut (and who knows, perhaps Retina resolution as well). So at this time the larger gen 3 and gen 4 iPads are the optimal iPads for display of critical color. It is possible to color calibrate the iPad mini with Datacolor’s SpyderGallery application, to produce corrected color (within the limits of the reduced gamut) in the Gallery viewer, or in other Apps if you launder your images through SpyderGallery. But for color critical uses, it may be worth holding off for a generation, to see what Apple has up its sleeve next time for the iPad mini.

Credits: C. David Tobie, Copyright 2013.   Website: CDTobie.com   Return to Blog’s Main Page

Advertisements

Color Analysis of the iPad mini

Note: I am republishing this article, as it pertains equally to the new Retina Display iPad Mini, which shares similar screen color with the non-Retina version.

Characteristics of the Fourth Generation iPad with Retina Display

There are not too many surprises with the fourth generation full size iPad (wouldn’t it be great if Apple gave these products functional names?). Its largely a refresh for the sake of updating the processor and moving the connector system to the new Lightning Connector. Both worthwhile improvements, but not anything to concern us here. Still, there are more questions to be considered with the new iPad mini.

Characteristics of the iPad mini

The screen of the iPad mini offers the pixel-count of the pre-Retina iPads, in a smaller form factor. Not retina resolution, but somewhere in between the non-Retina full size iPads, and the Retina versions, by way of its decreased screen size. Many will choose to live with this enhanced, but not “Retinaed” resolution (yes, I just turned Retina into a verb) in return for the convenience of the smaller form factor and the lower price of the new mini. But what about its color characteristics for serious uses? Has Apple taken a step backwards there as well, in order to make the new mini more cost competitive in its (already populated) size range?

Earlier Testing

The answer is yes, and no. As we know from previous testing, the Retina iPad screens (and the iPhone 5 Retina screen as well) have been updated from the earlier, twisted, sub-sRGB color space of early iOS devices, to a color space very close to sRGB. The gamut plot below shows the iPad 3, with sRGB overlaid, as that order provides the clearest indication of their match.  The green primary of the iPad 3 actually exceeds sRGB by a bit, but overall this is a great match.

sRGB gamut over iPad3 gamut

We have also studied the gamut of earlier iOS devices, and seen how this gamut effects their display of web images (in sRGB) and web videos in Rec-709, which shares a number of key characteristics with sRGB. The image below is the second generation iPad, overlaid on the third generation iPad, showing the smaller and twisted gamut of the earlier screens. There is no doubt that the color accuracy of the sRGB-sized recent devices is superior to the older devices.

iPad2 gamut over iPad3 gamut

Color of the iPad mini

With that background information in mind, lets look at the gamut of the iPad mini in relation to sRGB. First, its important to note that the white point (global color tone) of the iPad mini is close to the target value of 6500K, and the gamma (ramp from black to white) is very close to the target value of Gamma 2.2. In the image below, you will recognize the earlier, sub-sRGB gamut, and twisted primaries, with the added twist of primary green, and well as primary blue, being offset sufficiently from the sRGB primaries to lie outside of sRGB, making color correction that much more difficult.

iPad mini gamut in blue, compared to sRGB in red

Conclusion

Yes, this gamut looks quite familiar, as you can see by comparing it to the previous illustrations. The iPad mini does indeed revert to the smaller, twisted shape of the earlier iOS gamut. Apple seldom takes a step backward in their relentless move forward, but here we have one example of it. So, if you were considering getting an iPad mini for use as a photo or video portfolio, please note that these color deficiencies will effect your results.

It is quite likely that in the next generation of iPad mini, Apple will move the device forward to a full sRGB gamut (and who knows, perhaps Retina resolution as well). So at this time the larger gen 3 and gen 4 iPads are the optimal iPads for display of critical color. It is possible to color calibrate the iPad mini with Datacolor’s SpyderGallery application, to produce corrected color (within the limits of the reduced gamut) in the Gallery viewer, or in other Apps if you launder your images through SpyderGallery. But for color critical uses, it may be worth holding off for a generation, to see what Apple has up its sleeve next time for the iPad mini.

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

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

New iPad Color Article’s International Traffic

Most Frequent Visitors by Country

The article I published last Friday afternoon on the color gamut of the new iPad had received well over 5000 views by the finish of the weekend. One interesting statistic that can be derived from the Stats section of the WordPress system is what countries the blog’s page reads have been coming from. Take a look at the top sixteen countries noted for this blog, and see if the list looks at all familiar.

The ten countries where the new iPad was released on Friday were: US, UK, Canada, Australia, Germany, Singapore, Japan, France, Hong Kong, and Switzerland. A quick look at the list above shows that those who live in, or near, the initial release countries have been the most frequent visitors to the site, and to the articles on iPad color. There are five European countries and one Asian country within this section of the list where the iPad is not yet launched; however all of those, except Korea and Finland, abut a country where the iPad has been released.  And, with the possible exception of Finland, I would expect the second release of the new iPad will cover all of these countries.

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

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

And for further information about iTunes and color conversion for iPads see:

More Answers about the iPad and Color

Apple described the gamut of the new iPad as “44 percent greater color saturation.” Which left us without much of a standard of comparison. After receiving an iPad3 today, I tested its color gamut, whitepoint, brightness, and screen detail against an iPad2. The graph above shows the increased color gamut. It also represents what I would call a “normalized” color gamut, in that the primaries are now more closely aligned to what we expect red, green, and blue to be. I haven’t attempted to do the math to see if the larger gamut is actually 44% larger, as this would only be for this specific iPad3, over this specific iPad2, so would not necessarily be representative in the way that the larger sample Apple could test would be. But it is significantly larger. Which has two noticeable effects: more saturated colors at the extremities, and different color in other areas which both tablets can reach.

sRGB gamut over iPad3 gamut

The second illustration shows the gamut of the new iPad with the gamut of the sRGB colorspace superimposed on it. I chose this order of layering, as there is more area in the iPad’s gamut that is outside of sRGB than the other way around, though as you can see at the bottom of the illustration, there is a sliver along what’s known as the purple line (from saturated red to saturated blue) where the new iPad does not appear to reach the limits of sRGB. On the red to green edge of the triangle, the match is excellent, and the mismatch on the green to blue edge is in the iPad’s favor; though without color management, no mismatch in any direction is actually favorable.

The ideal way to reproduce colors on a device is to have a larger than needed gamut, and to use color management to display the correct colors out of that larger range. The easy way to avoid color management is to attempt a one-to-one match between the two gamuts in question. The illustration above shows that Apple has gone for the easy fix, and created a screen with a gamut very close to sRGB. As long as the files sent to it are in sRGB, this should produce a reasonable match, certainly a much better match than the smaller and skewed gamut of the earlier iPads, and other iOS devices.

Viewing sample images on both iPads confirmed this effect. I first calibrated each iPad with a Spyder4, then viewed test images in the Datacolor SpyderGallery app, where the color profile can be turned on and off at will. The following are my comparison notes:

* With color management off on both screens, the color did not match between them. The iPad3 was considerably closer to matching the same image on a calibrated desktop display, however.

* Turning color management on made a big difference (as it has always done) on the iPad2.

* Turning color management on made a smaller difference on the iPad3; and often in the other direction.

* Matching between the iPad2 and iPad3 was excellent for in-gamut colors once color management had been turned on for both.

* Matching for out-of-gamut colors was closer, but not identical between them with color management.

* Yellows, in particular, look different on the iPad3 than on the iPad2, to the degree that memory colors, such as the logo color of SpyderGallery, look considerably different. Since there is no color management at the OS level, this cannot be corrected or changed.

*Density corrections in SpyderGallery still improve shadow detail on both iPad2 and iPad3; apparently there was not change in default gamma, even with the change in gamut.

* Default whitepoint on both iPads is very close; unlike the white points of my iPhone 4s versus my iPhone4, where the difference took some time to get used to.

*Maximum brightness of both iPads is, amazingly, identical. Earlier iOS devices have had a significant variation in max brightness, so its basically a coincidence that the iPad3 I received happened to be exactly as bright, today, as  my year old iPad2 is. My iPad2, when it was new, scored the highest brightness of any iOS device we tested, so having it still be as bright as a new iPad3 today is not surprising.

Next; the other factor that everyone has been waiting to hear about: the “retina display” screen. Let me start here by saying that an iPad 2 and an iPad3 are very similar to hold, with the weight difference being pretty much indistinguishable, and the difference in the lip profile minor. In your hands, the easiest way to tell which is which is by the larger camera filter on the back. On a desk, the easiest way to tell is by the slight thickness increase with the iPad3.

Given the degree of similarity, I mixed the two devices up repeatedly while handling them for comparison. So when I did my image detail comparison, it was truly a blind test, as I couldn’t even remember which iPad was which. The answer may not be what you are hoping to hear: the increased resolution is real, but not large. At 24 inch viewing distance or greater it is more or less indistinguishable (with good vision, or reading glasses to correct it). At 12 to 18 inch viewing distances, where close viewing of the iPad is more likely to occur, it is clearly discernible in type, but less so in images. Depending on where you images came from, and whether they were downsized for the iPad (as images coming in through iTunes are), there may be no difference at all. I expect that iTunes may start creating larger images for download to iOS devices. Certainly when viewing images from my Facebook library on both iPads, the resolution and compression Facebook has chosen for my images is low enough that there is no additional detail or sharpness with the iPad3. On images imported via the iPad Camera Connector, sharp and detailed images did indeed show sharper detail on the iPad3. You almost have to look for it to see it, but once you see it, its quite obvious.

So, my conclusion, which is surprising even to myself, is that the increased resolution in the iPad3 is nice, but not killer. While the increased gamut is much more noticeable. My second conclusion is that images on the iPad3 are closer to correct color automatically, thanks to the closer-to-sRGB screen gamut, while images viewed through SpyderGallery with a custom profile are more accurate still, though the difference is less with the iPad3 than it is with the iPad2. And my recommendation is that people  probably don’t need to run out and upgrade, unless they are using their iPads as photographic portfolios and other color critical uses, where the extra gamut, and closer match even in non-color-managed apps, matters more than in most other uses.

And as a footnote: The SpyderGallery wireless communication, calibration functions, color managed viewing functions, and remote viewing functions for Facebook and Flickr all seem to work excellently on the iPad3. I don’t anticipate any need to for an iPad3-specific update to the app.

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

Color Management and the iPad

iPad 2 gamut in White, sRGB gamut in Green

As interest in the new iPad, with its higher resolution, larger gamut screen, comes to a head this week, I am hearing more and more about using the iPad as a photo portfolio, and other color critical uses. This, in turn, raises questions about color management and the iPad. While we will have to wait until Friday to be able to discuss color management in relation to the “New iPad” as Apple calls it, we can talk about color management in terms of other iOS devices in advance.

The image at the top of this post is a measurement for the gamut of an iPad or iPad2 (they both use the same screen). Its a bit more complementary than other measurements I have made on other iPads and iPhones, but overall they tend to have a fairly similar color gamut. This gamut is high in the blues, with no deep blue capability, and similarly short on the reds, making a really satisfying Christmas red out of reach, plus rather yellow in the greens, which makes images of lush greenery a rather unsatisfying duller tone than expected.

As soon as I received the original iPad, I looked at a standard color test image on it and diagnosed this set of color limitations without even measuring the screen. But measurements soon backed up my visual impressions, and I was immediately interested in the puzzle this laid out: would it be possible to color manage the iPad, as one would a regular monitor? If so, what methods could be used, since standard color management at the operating system  level was conspicuously absent in iOS. And would users be satisfied with the results, since color management for screens these days is more about choking back the display of images on high end graphics displays with a gamut much larger than sRGB, not attempting to display images on a gamut significantly smaller than sRGB.

Color Management On and Off on the iPad

The short answer to these questions is: Yes, Datacolor was able to develop a color management application for the iPad (and more recently for the iPhone as well; and we now have Android in our sights). And that app, named SpyderGallery, did indeed improve color on the device; though only within our own image viewing app, since the process called “sandboxing” keeps apps from interacting under iOS the way they can under desktop operating systems. And the SpyderGallery app even offers two rendering intents, for different types of images or different user preferences, that can be changed at will as the app is presenting images. The image above is an emulation of the results of toggling the color management switch on and off in SpyderGallery, showing a difficult image with, and without calibration. Sorry for the flashing effect while you are trying to read, but the before and after effect is important enough that I was willing to break that rule this one time.

SpyderGallery is, to date, the only color management app for iOS. It works by using a Datacolor Spyder3 or Spyder4 connected to your computer, which in turn communicates wirelessly with your iPhone or iPad, to coordinate the display of color patches, reading of those patches, creation of a color profile, and transfer of that profile from the computer to the iOS device. This process is illustrated in this screenshot of that section of the software below.

Once the iPad or iPhone is calibrated, you can view any of your images from the photo galleries on your device though the gallery component of SpyderGallery. This is unusual for an image app under iOS; most apps force you to import your images into their own internal gallery, leading to a constant mismatch between what you have on the device, and what you have in the app, and taking up twice as much precious hard disc space with the repeat copies of images. As well as viewing your iPhone or iPad galleries, SpyderGallery also allows you to access  your Flickr and Facebook galleries directly from the web, and apply color management to them as well. This increases the number of images and albums which you have color control over.

SpyderGallery displaying images from the iOS device's native galleries

One last tip for adding color management to your presentation applications and other apps under iOS. If you bring up an image in SpyderGallery, and take a screenshot of it, you will then have a full screen, color corrected image which you can crop or adjust as desired, and place in any iOS app, to provide color management outside of SpyderGallery.

Now we all have to wait until the new iPad is released on Friday, to see just how its increased color gamut and increased resolution interacts with SpyderGallery; and whether an update will be needed to the SpyderGallery application for any of the new functions in the new iPad.  Stay tuned for more on the topic, once the new iPad is out! For more information on SpyderGallery see the SpyderGallery Product Page.

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

Questions about the new iPad and Color

iPad 2 gamut in White, sRGB gamut in Green

Apple has made a rather difficult to understand statement about the color of the new iPad. They say it has “44 percent greater color saturation.” That is not a technical definition. Saturation is a linear (gray to high saturation) function, but an increase of 44% on a linear scale would mean a huge increase. If they are referring to the more common “percentage of sRGB” type of figure, than that would be more likely, but is still a pretty large increase in the color gamut of the device. If its in a three dimensional color space, then a 44% increase would be smaller still.

The various generations of the iPhone have all had fairly similar color gamuts (though the whitepoint tends to jump around a bit), and that same, rather quirky, gamut is also what the first two generations of the iPad offered. Reds fall short of sRGB red, green is twisted towards yellow, and blue is high, not offering a deep blue.

This type of small colorspace is all we have ever seen on an Apple mobile device, so the new iPad will indeed be interesting, and has the potential to be a much superior device for photo portfolios and other color sensitive uses; in addition to the unquestioned superiority that its higher pixel count screen will provide. I have a new iPad slated for delivery to my studio on Friday, March 16. So I will take a look at it then, and measure its primary colors, whitepoint, luminance, and other factors, to compare it to other devices. I will put up a post with some of that data once I’ve had a chance to test it.

So stay tuned for another post on this topic at the end of the week. Perhaps I’ll name it “Answers about the new iPad and Color” for the sake of consistency…

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