Notes on the iPhone 4′s “Retina Display”

By  |  Thursday, July 1, 2010 at 12:23 pm

[A NOTE FROM HARRY: Here's a guest post by my friend Dr. Ray Soneira, founder of DisplayMate Technologies, whose display-testing products are widely used by manufacturers and tech publications.]

The article by PJ Jacobowitz “Is the iPhone 4′s LCD the Best?” on PCMag.com with lab measurements comparing four high-end smartphone displays is especially interesting because it has the first published lab results for the iPhone 4 Retina display. Below are my own comments for some of the PCMag article results.

The iPhone 4 is 25 percent brighter than the iPhone 3GS, which was the previous record holder, so the iPhone 4 is now the brightness king for smartphones.

Steve Jobs promised a Retina display Contrast Ratio of 800 and PCMag measured 1097, 37 percent more than the Apple advertised spec. That’s very impressive because you seldom ever see manufacturers conservatively understate their specs to that degree – but then see my widely reported (and often misquoted) comments on the iPhone 4 Retina Display, where it falls short on that spec. The iPhone 4 is a tremendous improvement over the iPhone 3GS, which only had a measured Contrast Ratio of 138. But note that the Motorola Droid remains the Contrast Ratio king of mobile LCDs with 1436, which I measured in our own DisplayMate Lab tests.

The PCMag lab test result that really surprised and disappointed me was the small iPhone 4 display color gamut, which is only 64 percent of the industry sRGB/Rec.709 standard color gamut that is necessary to obtain accurate color reproduction for videos and photos. As a result all iPhone 4 images will have colors that are somewhat under-saturated and on the weak side. The same was true for the iPhone 3GS and all previous iPhones and iPods. I was really expecting the iPhone 4 to correct that deficiency and perform as well as the Motorola Droid, an IPS LCD that matches the standard color gamut almost exactly and delivers essentially perfect color accuracy images, as good or better than most HDTVs. So the iPhone 4 is disappointing in color saturation and color accuracy, but is state-of-the-art in pixel resolution and sharpness.

On the other hand, the PCMag lab tests found that the HTC Droid Incredible had way too large a color gamut and color saturation, the same as the Nexus One and most OLED displays on many phones. While that often gets an initial “wow” response – even from reviewers who should know better – too much image color and coloration in photos and videos is actually visually worse than too little color. So the iPhone 4′s less than ideal weak color is actually visually better and preferable to all of those OLED displays that have excessive color – unless you prefer gaudy colored images.

While the iPhone 4 LCD has a significantly lower Contrast Ratio than OLEDs, which typically have Contrast Ratios of 30,000 or more, it’s not particularly relevant for mobile displays because they are typically viewed under bright ambient lighting, where screen reflections of the surrounding ambient light are much greater than the display’s own internal black level. The Contrast Ratio spec only applies for viewing in the dark. The iPhone 4′s bright screen and low reflectance means that it delivers a much higher REAL screen image Contrast under typical ambient lighting than OLEDs, which are not as bright and have inherently higher screen reflectance than the iPhones. But in dark ambient lighting the OLEDs deliver outstanding Contrast.

In the near future I will be reporting on our own intensive DisplayMate iPhone 4 display lab tests, with in-depth evaluations and analysis and some comments on how manufacturers can improve their mobile displays.

 

 
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3 Comments For This Post

  1. Pascal Cuoq Says:

    I am neither a graphic designer nor a native english speaker, but it is my understanding that a screen cannot have "too large a color gamut", although it *can* display over-saturated images. Having a color gamut that exceeds sRGB is useless especially on a phone presumably without software support for ICC profiles (http://en.wikipedia.org/wiki/ICC_profile ), but it doesn't hurt.

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