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Evaluating the MacBook Pro 15 inch LED-backlit display  
Saturday, July 7, 2007 | by Rob Galbraith
LED backlighting is touted as a breakthrough flat panel display technology, owing to its promise of a wider colour gamut, more even screen illumination, longer display life and greater power efficiency. Plus, unlike the Cold Cathode Fluorescent (CCFL) illumination found in most flat panels today, LED is mercury-free. This all sounds good, but does it translate to Apple's newest MacBook Pro 15 inch - which is the first laptop of its size to incorporate an LED backlight - being better than previous Apple laptops for the viewing and editing of pictures? Here's what we found.
 
Light Display: A MacBook Pro 15 inch with LED-backlit screen, surrounded by monitor calibration hardware. Click to enlarge (Photo by Rob Galbraith/Little Guy Media)
 
A brief history of laptop displays
 
First, some background. Back in the days when the big differentiating feature in laptop screens was whether they were passive or active matrix, the one thing all such displays had in common was their terrible colour. They were terrible before calibration and profiling, and they were terrible after too. It was a guessing game trying to judge image exposure and white balance, while adjusting tone and colour in Photoshop needed to be done by the numbers, for those brave enough to attempt it at all. This was life as a mobile digital photographer in the 1990s.
 
All this changed for us with the introduction of new Apple Powerbook G4 models in the spring of 2002. Earlier models in the same Titanium enclosures featured a 15.2-inch, 1152 x 768 pixel display that responded poorly to calibration (think purple highlights and green faces). But in April of that year, Apple switched the Powerbook G4 "TiBook" to a 15.2-inch, 1280 x 854 pixel screen that - for the first time in our experience - responded well to hardware monitor calibration. So well, in fact, that we finally felt comfortable that what the screen was showing us was close to what our pictures actually looked like. Armed with the right monitor hood, it was possible to even adjust pictures in Photoshop with confidence. For the on-the-go photographer in the early part of the new millenium, this screen was a big leap forward.
 
Apple continued to use this display, or at least equally photo-friendly ones with the same 1280 x 854 pixel resolution, through numerous subsequent revisions of Titanium- and Aluminum-encased 15-inch Powerbook models. They also introduced a 17-inch Powerbook G4, and its 1440 x 900 pixel screen was almost as good as its smaller 15-inch counterpart. During this period, we struggled to find a laptop from any Windows PC laptop maker that measured up (of the dozens of photographers' laptops we tested at various workshops, all exhibited lousy colour before and after calibration).
 
But by 2005, things had improved on the PC side too, thanks to improvements in the 1280 x 800 pixel and 1440 x 900 pixels screens found in practically every maker's 15.4-inch and 17-inch laptops at that time. These displays (which probably came from no more than two or three laptop display suppliers), coupled with a new laptop calibration mode introduced in then-GretagMacbeth's Eye-One Match calibration software, meant for us anyway, laptop screen quality was something to relax about.
 
While laptop screens didn't yet deliver the colour fidelity and fairly even brightness of better desktop flat panels, we encountered plenty that crossed the threshold of usability for image assessment and even basic image editing in the field. But we never did find a non-Apple laptop in this period that could quite match the overall level of colour quality of the Powerbook G4 15 inch's 1280 x 854 pixel display, and as a result we expected that Apple would continue to be the company to beat in this regard.
 
Shortly before the Powerbook G4 line was retired, Apple introduced new 15 inch and 17 inch models with revised, higher-resolution displays. We never laid eyes on either one, so our brief history picks up again with the introduction of the MacBook Pro in the first half of 2006. The new 15 inch and 17 inch laptops, the company's first to feature processors from Intel, also incorporated new displays: a 1440 x 900 pixel screen in the 15 inch, and a 1680 x 1050 pixel screen in the 17 inch.
 
In anticipation of some upcoming training work, we gathered and calibrated/profiled both models at settings that had worked well on previous Apple gear:
  • White point: 6000K
  • Gamma: 2.2
  • White luminance: 120cd/m2
We judged the results, then immediately yearned for the return of Apple's older 1280 x 854 pixel screen. The older display wasn't perfect - even when calibrated and profiled optimally, photos showed some posterization in deep shadows, midtones were a bit too light and the screen was uneven top-to-bottom, which made it important to find the same viewing angle each time. Knowing these things, however, and knowing that each shortcoming wasn't too severe, made it possible to trust the screen.
 
Not so with either model of MacBook Pro. Various hues were wrong: skin tones were overly yellow-green, for example, and gray balance in light greys was a bit too far off. Other colours were oversaturated. The usable viewing angle of the screen was also too narrow; shifting an inch left or an inch right changed the hue of certain colours noticeably, while tilting the screen up or down slightly showed not the typical top-to-bottom uneveness in brightness, which can be worked around, but instead a contrast and density shift on the top and bottom of the optimum viewing area, a shift that made it look like some of the screen had a plastic film overlaid. We tried reprofiling at each screen's native white point, but that didn't help.
 
On their own, none of these deficiencies was a deal-stopper, and even together, these screen deficiencies didn't mean the displays were terrible, like in the early days of digital. But it did push them over to the wrong side of the line of usability for photo viewing and editing. Both site co-editor Mike Sturk and myself own 17-inch MacBook Pros, and they're wonderful computers in most respects. But this model's screen, like its 15-inch counterpart, has been at best only marginally okay for the purpose of working on pictures in the field. And neither model's screen has been up to the overall level of what has come before from Apple.
 
Which is why we've been eagerly awaiting the introduction of MacBook Pros with LED backlighting. Not because LED illumination was going to automatically cure all, but because it represented an opportunity for Apple to get back to the business of making laptops with the best-available displays in their size. This would be a good thing for Mac users specifically, and the industry generally. On June 5, 2007, we got half of what we've been waiting for, when Apple introduced a new 15-inch MacBook Pro with LED backlighting (the 17 inch soldiers on with a CCFL backlight). We've now put the new screen to the test, and the next section describes our results.
 
Note: See the section But wait, there's more later in this article for a partial solution we've discovered to the colour quality problem of MacBook Pro CCFL screens.
 
Evaluating the MacBook Pro 15 inch with LED backlight
 
Okay, let's end the suspense: the new Macbook Pro 15 inch's screen is very good.
 
We came at it armed with four monitor calibrators and as many calibration software packages, but we needn't have. Calibration peformed with any of the hardware/software combos we have on hand resulted in a more colour-accurate view of photos than is possible with past MacBook Pro screens of any size, and the combination of the Eye-One Pro spectrophotometer and Eye-One Match 3.6.1's laptop calibration mode generated such a good profiled result that we're comfortable saying this screen is the best we've ever seen in a laptop, not only because the colour accuracy is decent, but also because of a noticeable improvement in centre-to-corner display evenness.
 
It's still not up to the quality of a desktop display, for several reasons, including the fact that a couple of colour quirks remain - things that are a deep orange are rendered as a deep red, for example, regardless of calibration - and the screen still suffers from the narrow viewing position problem of its predecessor, though because it's relatively free of oversaturated colour weirdness, the colour shifts brought about by changes in head position are less noticeable and less troublesome.
 
We arranged three laptops side-by-side: a second-generation MacBook Pro 15 inch, second-generation MacBook Pro 17 inch and third-generation MacBook Pro 15 inch (the current model with LED backlighting). All had matte-finish screens. All were calibrated and profiled with an Eye-One Pro spectrophotometer and Eye-One Match 3.6.1, and their backlight brightness was set before profiling to hit a white luminance target of 120cd/m2.
 
Then, we put up the same collection of 45 photos on each computer, ones we've amassed over the years to check out monitors. While cycling through the pictures, we compared each laptop's display to the other while also comparing all three to an Eizo ColorEdge CE240W (a display whose colour is poor when viewed off-angle but impressively accurate when looked at head-on).
 
monitor_cal_screenshot.jpg
Through the Looking Glass: A monitor test photo displayed on Apple's new LED-backlit MacBook Pro 15 inch (Photo in screenshot by Rob Galbraith/Little Guy Media)
 
The inescapable conclusion is this: calibrated and profiled as described above, the screens in the older 15-inch and 17-inch MacBook Pros don't quite cut it, but the new MacBook Pro 15 inch model with LED backlighting displays colour that's pleasingly close to the mark. And while the new laptop has the same tight viewing angle as the older models, it's less of a problem in reality because of the aforementioned near-elimination of colour oversaturation problems.
 
Overall, the new laptop's display surpasses our previous standard bearer, the very good 1280 x 854 pixel display in the Powerbook G4 15 inch of yesteryear. It calibrates equally well, has the same one or two minor colour quirks but shows smoother transitions into deep shadows and is much more even in brightness across the screen. Plus, the promised longer service life of LED vs CCFL should translate into the MacBook Pro 15 inch's screen retaining its finer attributes farther into the future. The King is dead. Long live the King.
 
We mentioned off the top that a potential advantage of LED-backlit displays is a wider colour gamut. This is true of the LED-backlit screen of the new MacBook Pro 15 inch, but when compared to the CCFL-backlit screen of its predecessor, gamut volume has grown only from small to less small. In fact, the colour gamut of the MacBook Pro 15 inch with LED backlighting is still quite a bit smaller than that of a reasonable-quality desktop flat panel with a CCFL backlight.
 
The gamut plot on the left is a representation of the MacBook Pro 15 inch with CCFL backlight; on the right is that of the MacBook Pro 15 inch with LED backlight. If you hold your cursor over the left plot, it will change to show the gamut of the LED-backlit screen. If you hold your cursor over the right plot, it will show the gamut of an early-2006 iMac 20 inch.
 
As you'll see, the LED-backlit MacBook Pro 15 inch's colour gamut is larger than the CCFL-backlit model it replaces, but both are dwarfed by the iMac 20 inch's colour gamut (which is fairly close to the gamut volume of sRGB).
 
Rollover image
The Plot Thickens: A gamut plot of the MacBook Pro 15 inch (CCFL-backlit model). Hold your cursor over the graphic above to see the colour gamut of the MacBook Pro 15 inch with LED-backlit screen Go Wide: A gamut plot of the MacBook Pro 15 inch with LED-backlit screen. Hold your cursor over the graphic above to see the colour gamut of an iMac 20 inch desktop
 
While big gamut gains may be found in the few present and many future desktop displays sporting LED illumination (and this is probably especially true of those with tricolor LEDs), the LED-backlit display in the new 15-inch MacBook Pro only brings about an incremental improvement in colour gamut.
 
To sum up, the new MacBook Pro 15 inch's LED-backlit display is very, very good. It's the best laptop display we've seen and one we'd use in the field without reservation. But its minor colour quirks, tight head position requirements and relatively small colour gamut when compared to a desktop display means there's still lots of room for improvement in future laptop offerings. But for now, the MacBook Pro 15 inch with LED backlight is definitely a step up from any laptop display we've looked at before.
 
But wait, there's more
 
The good news doesn't stop there: in the course of testing the new MacBook Pro, we stumbled across a counterintuitive way to calibrate older MacBook Pros that happens to eliminate their key colour quirks, which in turn moves them back into the suitable-for-viewing-and-basic-editing category. The process is fairly simple:
  1. Run the calibration once normally, adjusting the screen's backlight control (the Brightness slider in the Displays system preference) to reach the desired white luminance (120cd/m2 in our case). If your monitor calibration package allows for this, you can stop the calibration process once you've set the Brightness slider. Note that you can also adjust screen brightness using the computer's dedicated function keys for this, but the Brightness slider in Displays steps the backlight up or down in finer increments.

  2. Then, record the position of the Brightness slider. About the easiest way to do that is to take a screenshot. Command-Shift-3 will grab a picture of the entire screen, while the more-useful Command-Shift-4 will enable you to select what you want captured.

  3. Move the Brightness slider all the way to the right to full brightness, then run the calibration from start to finish with the same parameters (ie 6000K, 2.2 and 120cd/m2), but this time skip the step where you adjust the backlight. In other words, run the entire calibration with screen brightness at maximum.

  4. Once you've completed the calibration and saved a profile to your system, set the Brightness slider in Displays back to the position you noted in step 2. Keep the screenshot, since you may accidentally (or intentionally) adjust the screen brightness later, then need to set it back to the optimum position.
With both the second-generation 15-inch and 17-inch MacBook Pros, performing the calibration this way eliminated several of the colour accuracy gripes we've had with these displays, and was repeatable with more than one monitor calibration package, so it's likely not a fluke but rather a way to work around something strange about how these displays respond to profiling when their CCFL backlight is dimmed first.
 
By our own subjective standard of acceptability, the older machines' displays now pass the test when profiled this way. The only apparent hitch in this oddball calibration technique is a slight loss of deep shadow gradation: to be precise, shadows block up at tone level 4 of 256 in Adobe RGB, as compared to level 2 of 256 in the same colour space when white luminance is set before profiling. Given the other benefits, this is a loss we can live with.
 
The new, LED-backlit MacBook Pro 15 inch still has the better screen. It's more even in brightness across the entire display surface, deep, deep shadows are slightly more true, it has a somewhat wider colour gamut and it's likely to maintain usuable brightness for longer - perhaps years longer, based on some estimates - than a CCFL-equipped laptop display. The switch to LED also makes the MacBook Pro 15 inch a bit lighter, and the promised runtime on battery longer too. But our accidental discovery of a way to better-profile the older MacBook Pros we already own means they should serve us well for awhile yet.
 
Note: The trick described in this section should work with first-generation MacBook Pros as well, since we've previously found their screens to profile the same as second-generations ones. What about the third-generation MacBook Pro 17 inch, introduced alongside the 15 inch LED model last month? It's unlikely that Apple made changes to its standard 1680 x 1050 display, but we've not actually tested one, so it's only a guess that it should profile as well as the second-generation 17 inch. The 1920 x 1200 pixel display option for this model is all new and we can't predict how it will respond to calibration and profiling.
 
Testing notes
 
The MacBook Pro 15 inch with LED backlighting was calibrated and profiled several different ways with four different monitor calibration hardware and software combinations (white point, gamma and white luminance is in parentheses):
The best result was obtained with the Eye-One Pro and Eye-One Match set to 6000K, 2.2 and 120cd/m2, but any of the other three combinations also were reasonable, with only the profiling performed with the Eye-One Display 2 being visibly poorer than the others (Update: with this specific instrument, we've found that profiling at a screen's maximum brightness can help reduce some of the colour quirks it causes, with laptop and desktop screens alike).

This wasn't meant to be a test of monitor calibration packages but of the new MacBook Pro's display, so we stopped short of trying all possible hardware and software combinations, including the Eye-One Pro with ColorEyes Display Pro, which should work at least as well as this instrument does with its own software.
 
Non-glossy displays have been in all the various MacBook Pros we've calibrated and profiled over time, prior to and for this article, so if your MacBook Pro has Apple's optional glossy surface it may respond differently to calibration.
 
All pictures used for evaluation were shot with Canon and Nikon digital SLR cameras; most were in the Adobe RGB colour space. The test also included white-to-black, shadow and highlight ramps, in Adobe RGB. The best laptop displays are clearly still a couple of notches below desktop displays of reasonable quality, so evaluating them means not worrying too much about subtle colour errors and instead looking out for display weaknesses that could cause mistakes like selecting a less-than-optimum white balance during RAW conversion, making a tonal adjustment in Photoshop that renders the picture lighter or darker than it ought to be or correcting for an apparent hue problem that doesn't actual exist in the picture, only in how the screen displays the picture.
 
Thanks to Peter Jeune and John Melnyk for the loan of their new and old MacBook Pro 15 inch computers, and thanks to Gary Astill of Lastolite for the superb Studio Cubelite product photography kit - used for the lead picture in this article - to replace our decaying home-grown setup.
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