Monday, November 28, 2005

First Camera Profiling Results: Ron Donson

Photographer Ron Donson has graciously allowed me to post images from his profiling experiment. Here they are. Decide for yourselves which sandwich you prefer. Both images are copies of the same file, one was left in AdobeRGB, the other had a profile I made for Ron assigned. Both images were then levelled out identically (by numbers) resized and converted to sRGB with relative intent, and posted.

Please copy-paste the following links for downloads. Tabs are neat for flicking back and forth between the two images.

I'll let you vote in the comments for which you prefer.


Sunday, November 27, 2005

The Camera Profiling Experiment Rules

I've started to attract a lot of visitors interested by my offer of free camera profiles. I'm not doing this out of the goodness of my heart, I'm doing it to gather experience in what works and what doesn't.

You send me a target, and a couple of photos created with the same lighting and settings. Preferably all of the above are in-camera Jpegs, otherwise identical Raw conversions. No photos that allow me to evaluate the work means no profiles.

If you send me in-camera Jpegs, that means 2 files (One chart, one sample).

If you send me conversions, that means 4 files, preferably:(Converted chart, converted sample, Raw chart, Raw sample).

Large files can be easily sent via

I'm summarizing the shooting guidelines below:

The target has to be very carefully lit, any gradient or colored reflection will damage the profile. One single softbox far away is good lighting, it can be masked or goboed to even it out. A mini colorchecker may have less lighting issues than the full-size one.

The target should not occupy the whole frame, to avoid vignetting prolems leading, again, to non-uniform lighting. It should not be cropped, I want to see the cardboard frame at the very least. If possible it should be mounted on some grey background.

Yes, lighting is crucial. The method I know off I learnt from the Coloreyes software - a respected profiling tool - which recommends ONE single softbox, slightly to one side, as far away from the chart as possible, feathered or goboed to make the illumination constant. An additional precaution is to move the card holder away from the back wall, in fact keep it away from every wall because of reflections, and also pay great attention to reflections on the camera. One thing I might do in the future is recommend two shots of a rotated target and create software to help me average out those shots.

TESTING: "The camera should be custom gray-balanced using whatever tools you usually employ for this. You can gray-balance in the Raw converter by clicking on your preferred target square."

The workflow must be locked down. Fixed conversionparameters, or in-camera Jpegs, please. The camera should be custom grey-balanced. And, if possible, the Lab value of the colorchecker white patch should be around 96, if this is the target you're using. You should almost be blowing out that patch, I think. Also, beware of lens vignetting ...

Canon's DPP is a very good converter to attempt this with.

When you get the profile emailed back, you simply assign it to your images in Photoshop.

You can send files to the address at the top of the blog. However, I will expect feedback as a condition of making the profile. A couple of additional images taken with the camera in similar lighting, sent with the target file are one of the requested peices of feedback.


Saturday, November 26, 2005

Color Management Books

I just received Andrew Rodney's new book, Color Management for Photographers, and Abhay Sharma's Understanding Color Management. Reviews will go up shortly, but here is the sneak preview:

Andrew Rodney's text shines as a howto book. It is simpler and more complete as a tutorial text than Real World Color Management. It'll teach you what a color-managed workflow is, why you want one, and how to get the job done with the main tools on the market. There's even a set of work-through exercises, and a very useful CD with a lot of demo software, sample images and other useful goodies.

Abhay Sharma's textbook explains all the color-geek stuff in terms simple enough to understand. This is where you'll find a clear definition of all that quaint terminology, like "tristimulus", and the background on colorspace conversion formulae . Dr. Sharma also provides information on how profiling software is architectured, and the actual contents of an ICC profile file, again in terms simple enough to understand.

Capsule summary: Both books are excellent, while very different. Professional and amateur photographers as well as users of color management technology in industry won't regret buying Andrew Rodney's book. Readers wanting to understand the concepts underlying CMS software and practice will find in Abhay Sharma's text an excellent introduction to the science behind the technology.

Dr. Edmund Ronald

DTP70 Bill Atkinson targets

The DTP70/Profiler combination is pleasing me more every time I use it. Bill Atkinson is well known for his Epson widebody profiles. He tells me he likes the DTP70 too, and he's made some targets for it, including one huge strip for wide-body printers, that the spectro reads ingests in one gulp. To make the strip feed in straight Bill has constructed an input tray for the spectro. You can find the Atkinson targets for the DTP70 here and a picture of Bill's setup at this site.

Saturday, November 12, 2005

Xrite's DTP70 and i1Match software play nice together

I've tried using theXrite DTP70 as a measuring instrument for Gretag's i1Match. It works.

I have an old i1 Rev A spectro, and the associated i1Match v3.0 software. Xrite supplies a very nice free, undongled app called ColorPort, which allows you to define targets and read them in.

So I read in the Gretag TC9.18 reference file, made myself a two-page A4 target for the DTP70, opened the Tiff files in Photoshop and printed them close to the edge, and read the targets into ColorPort with the DTP70. Then I exported the measurements from ColorPort into a CGATS file.

Finally, I connected the i1 Spectro (it's the i1Match dongle), read the CGATS file into i1Match, and made a profile. Bingo!

Compliments to Gretag and Xrite for behaving like adults and supporting industry-standard data formats !

I assume that PMP will be able to read the same CGATS files as i1, so one can doubtless use PMP as a backend for the DTP70. Neat !

DTP70 and Monaco Profiler 4.8 Review 'official" full text.

Xrite sells an automated print profiling solution, a bundle containing the Xrite DTP70 and Monaco Profiler 4.8. This is based on the DTP 70 spectro, which I started testing two weeks ago. It's been a very pleasant experience.

Until I started working with this Xrite combo, I didn't know printer profiling could be so simple. I was up and running in less than 30 minutes after unpacking the product, and inkjet profiles now take me less than 10 minutes to create.

The DTP70 is a fast compact device that acts like an inkjet printer in reverse: It ingests printed testcharts and scans them. Like an inkjet, it connects to your computer by a USB cable, and takes up little real estate. The only control on the device is the large button — you press this to tell the spectro to start scanning the chart you inserted.

The chart-scanning process requires only a couple of minutes per page. Yes, it's lightning fast!

The spectro hardware has both white and black backing strips for measuring. You can choose which to use by flipping the backing plate. Also, a UV filter can be manually rotated in and out of the measurement path at will—this is a very sensible design, as only some users and some software packages will need the filter. For the record, my position is that photographers who make client prints should not use the filter, while printers who make proofs should.

The Monaco Profiler Platinum software that Xrite supplies to drive the DTP70 has a comprehensive range of color management abilities. It can create scanner and camera profiles, calibrate monitors, create RGB and CMYK printer profiles, and edit ICC profiles. So far I've only exercised the printer profiling part of the package.

Installation of Monaco Profiler on my Powerbook under Panther was a breeze. The software can run anywhere, provided you plug in the dongle. My dongle got programmed remotely by the Xrite Web site during a registration procedure launched during installation. When installing on "fanjet", my noisy dual G5 with Mac OS X Tiger, I had a minor glitch as the HASP dongle driver didn't install automatically. As for Windows, the install on a Win XP machine at Canon's offices (see below) went through flawlessly.

I first profiled my home Epson 2100 inkjet, with two glossy papers and one matte paper, in RGB mode. For this, I used the half-page test chart, the simplest supplied by Monaco Profiler. I verified profile quality visually by means of a print of the Colorchecker template downloaded from Danny Pascale's site, updated with some of my own measured patch data. I also ran off the Pixl test image before printing some of my own portofolio.

When I was quite certain that my homemade inkjet profiles were good, I put the DTP70 in a plastic shopping bag and took it to visit Mr. Mariane, at Canon's headquarters in Paris. Together, we profiled a wide-body Canon inkjet, and a monster RIP-driven Canon laser-printer/copier that costs several hundred thousand dollars.

The copier yielded excellent color-accurate results for the Colorchecker, both in RGB and in CMYK mode, and made visually appealing photo prints, when our Xrite-generated profiles were used. However, to obtain optimal color from such an unstable device, the printer's self-calibration procedure should be invoked to re-linearize, before a print run and before profiling; also, color-sensitive prints should be run off as multiple copies, and the first few pages of each batch of prints should be disregarded.

No product is perfect. However the only weakness I found so far with the DTP70 is that the paper lead-in of a test chart needs to measure close to 30mm or else the paper mechanism will refuse to feed in. This makes it necessary to trim the charts by hand, precisely. But the Print with Preview dialog in Photoshop lets me print charts at exactly the right distance from the paper edge, on A4 sheets, and then the feed mechanism performs very reliably with no need for manual trimming of the page.

Capsule summary: The DTP70 and Monaco Profiler profiling combo is unproblematic to use and lightning fast. This industrial-strength profiling system is perfect for a production environment such as a repro-center or print-room.

I wish to thank Danny Pascale, the author of the Babelcolor color measuring and conversion software, Steve Upton, padrone of Chromix and author of the Colorthink profile evaluation tool, and color specialist Roger Breton for their invaluable assistance while I was struggling with ICC Color Theory 101 during this review.

Friday, November 04, 2005

DTP70 Review is up on

Click here for my "official" review of the DTP70!

I'm now going to shift my focus to the rest of the Monaco Profiler Platinum software, and also look at profile Editing.

I like the profiles I got with the small chart. Skin tones look ok on my Epson. No point in moving to the bigger charts IMHO. But I'm looking for a way to improve the linearization of the devices I'm using eg. cheap inkjets.

One of the big advantages of a fast profiling device is that you can easily experiment with the driver settings, in order to improve the final image.