Friday, September 16, 2011

PatchTool Review PART I: From Target Image to CGATS file and vice versa.

Danny Pascale's PatchTool

Nutshell Review: If you need to hand-measure profiling targets or generate custom target grids, or wish to convert the patch layout output by one program to that needed by another, then you might do well to get a copy of PatchTool . But in addition to its invaluable patch conversion functions, this utility now also provides a sophisticated quality assurance toolset that can be employed for display, printer, and instrument verification.

PatchTool is one of those small specialized color utilities which can pay for themselves in a single hour of use, by quickly solving a problem that could otherwise be done by hand, were there but world enough and time. 

I'll talk about the simple and basic patch stuff today, the rest I will deal with in Part II of this review in a few days. Let me tell you about the simple tasks in which PatchTool can help a color consultant or color management expert, and why they're essential.

PatchTool's basic usage is the conversion of target images to CGATS files and vice versa, and also changing the layout of the image corresponding to a CGATS file. It can switch columns and rows, rearrange the array to a predetermined number of rows and columns,  etc, It can also acquire data from an EyeOne spectro to measure a set of patches and generate a file, thereby allowing for the creation of custom targets and Photoshop swatch sets,  and measure on-screen. All of this is useful to  color consultants and power-users:

Every user of color management software knows that to profile a device one must print or photograph a target. Then, the colors of the target are described in the computer by a so-called CGATS file. In fact, it is common to speak of the target's CGATS reference file, which describes known values supplied by a manufacturer,  and the corresponding CGATS measurement file which is written out by the user's instrument driver software. Of course a reference file, eg for a Colorchecker  chart can itself be viewed as a file written out by the chart-measuring technician of the manufacturer who supplied the chart. 

To a certain point, CGATS files are compatible between pieces of software, but as always the devil lurks in the details. One piece of software writes measurements of a grid row by row; then a profiling package by a different manufacturer expects its inputs column by column. What now? Well it's time to find some conversion helper.  Which is where PatchTool comes and solves the issue by reading the first file and spitting out another with the columns and rows flipped ! 

PatchTool is a an utility that is there to fix little annoying details, and what is impressive is that it really helps to gets all these little annoying details just right so you don't have to write custom scripts. In the image above you can see the options provided for writing values into a CGATS file, line by line — and of course if you read in a file, and spit it out with different options, you've done a conversion. 

Another typical use of this type of software for me is custom-measuring my ColorChecker and ColorChecker SG targets. I find that my own chart data —from my personal measured targets —deviate enough from the generic published images and reference files, that it is worth to measure my targets myself and create my own reference files for camera profiling, and before doing a chart-to-print comparison or even a chart-to-screen comparison. Here PatchTool can help out by driving a spectro and then spitting out a measured CGATS file, and even an image of the core of the measured target.What more could one wish for? Well, just maybe templates of the cardboard target borders to overlay, or even  comparison "holey" Photoshop layered templates …

This completes my quick description of the basic functions of PatchTool; it's not really an in-depth review because I've had a need, and used the software for two days, and it's done everything I needed without forcing me to pause and think. I'll have an exploratory look and address the "power user" stuff in the next installment. 

By the way, I like to leave my readers with a pointer to some useful net freebie as a reward for getting this far. Today's resource is Danny Pascale's fan page for the Xrite Colorchecker target, which has Colorchecker images in every possible colorspace.  Download one of these images, get out your physical target, and check out your printer and monitor profiles !


Tuesday, June 21, 2011

i1DisplayPro - will Xrite move from proofing to viewing ?

Regarding hardware, the instrument is a strong followup to i1Display 2, Xrite says it is designed to be future-proofed for wide-gamut displays. I like the sexy design, and the fact that clipping it on a laptop screen really works. A carry pouch is just about the only improvement I could suggest for the hardware :)

Regarding software, i1Display Pro offers a hodgepodge of new features, which may or may not be useful, but at least Xrite is making an effort to explore the spectrum of functions that a colorimeter can fulfill. The old model was to view a calibrator as something to effect "dumb" calibration for proofing use with a D50 lightbooth in a "perfect" controlled environment. At some point we will have to decisively break away from this model, because it simply doesn't reflect the real-world everyday usage of computer displays which have become ubiquituous. 

Technology has evolved, I believe the high-contrast wide-gamut display IS the image now, rather than just a proofing device for pale yellowish paper. Files posted on the web are mostly clipped to sRGB, but when every display goes wide-gamut we will certainly expect to see more colors in every Facebook image of a rainbow.


Cute, tiny Xrite Colorimeter released

Xrite has released the cute, tiny Xrite ColorMunki Display and i1 Display Pro; both are display profiling solutions that center around a very nice colorimeter  that looks like a toy searchlight:

In the above image, the ambient diffuser cover which can fit over the lens has been rotated down to act as a tabletop support for the unit, which can be aimed at a screen for projector profiling.

Fear not, the device fits very snugly even on a laptop display when hanging from its USB cord, I know because I was a beta-tester. The cord actually bears a sliding push-in adjustable counterweight aka retaining clip that hooks over the display edge, and works wonderfully on laptops. 

Depending on the version, the software for this unit has zilliions of new features, among which display uniformity testing, and building profiles that take ambient light levels and display flare into account. 

Thursday, May 26, 2011

Calibrating the MacBook Pro display

Under review.

How White LED display backlights work.

All the new Apple laptops are now using screens backlit by LEDs, I believe. These backlights do not involve red, green and blue diodes, but rather blue diodes encapsulated in a phosphor coated epoxy. This coating absorbs the diode's light and fluoresces, and reemits some of the blue light frequency-shifted to longer wavelengths by way of a physical phenomenon named the Stokes shift. Result, white light, or rather a weird but still smooth spectrum:

White LED technology is displacing CCFL (fluorescent light-tube) technology in laptops, and even in large TV displays; I guess the advantages are low-voltage power supply, no slow flicker and hum,The obvious disadvantage can be seen in the spectrum diagram above: The power output in the longer wavelengths is abysmally low, so you can expect to have a reduced gamut in the reds — no wonder then that demo discs for TV showrooms are heavily stacked toward Ridley Scott bluish decors. 

If your inner geek is still hungry Wikipedia is begging to illuminate. The graph above was excerpted from the linked article.

Friday, May 20, 2011

Bug of the day: Epson Premium Luster and Premium Glossy profiles

Every day brings its bug report. Today I noticed that the two Epson profiles "Epson Stylus Pro 3880_3885_3890 PremiumGlossyPhotoPaper.icc" and "Epson Stylus Pro 3880_3885_3890 PremiumLusterPhotoPaper.icc" installed by my Epson 3880 driver appear to be identical. 

I don't think those inkjet papers are anywhere identical, do you? I think this bug may be biting professional inkjet users, as I believe that the 3880, 7880 and 9880 use the same profiles. I found the bug by accident when comparing gamuts. 


Monday, May 16, 2011

i1Profiler - Xrite pimps new software with innovative interface


I received the i1Profiler upgrade for my purple PMP dongle a few weeks ago, and have now played around a bit with the product. Xite support helped me quickly and effectively with some minor installation woes, when i1Profiler had a conflict with the installed ColorMunki software. I then ran a single-page target on the iSis to create a profile for my Epson 3880, on some old experimental Canon matte paper, and this profile was first rate.  Every other color geek seems to like the profiles too, although some deplore the absence of direct DTP-70 support (measurement files are accepted) and the fact that scanner profiling has been dropped.

 i1Profiler does display, projector and both RGB and CMYK printer profiles. It updates most of the features of old Monaco and PMP (see below), and wraps them in a very pretty but also truly innovative interface. This has a basic mode with plenty of online help for the non-specialist and a truly novel advanced mode for the color geeks. The innovation stems from the way in which it s possible to save settings or measured data - the saved states are symbolized by icons and called assets and workflows.  It's like nothing I've ever seen before, which is why I'm simply pointing you at the video. I think this interface is so interesting that people will copy it. 

 This blog has had a hiatus for a few years, but in that time, nothing really changed in the color world. Gretag got merged into Xrite, but the combined company marketed both Xrite's Profile Maker Platinum and Gretag's Profiler Maker Pro professional publishing software, and the prosumer i1Match series. All of which were visibly stuck in a minimum-maintenance mode.  They will now be retired as i1Profiler addresses both pro and prosumer in a very complete  one-size-fits-all package; most users will be quoted around $500 list for the upgrade, although there seem to be some better deals floating round.

 Prosumer sales and upgrades from i1Match will take off right now, but it may take more time until the prudent and conservative pro color community fully adopts i1Profiler, since many users are still quite happy with their existing packages. However, I do think Xrite has a solid winner here, and the release of 1Profiler demonstrates that the company has fully digested the merger and the Pantone acquisition, and can now move ahead again with product development.

 I'll come back with a more detailed look at some of the i1Profiler features, reasonably soon.

Edmund Ronald