Friday, December 14, 2012

What about this Media White Point?

The "wtpt" (media white point) tag of a display profile should be D50 regardless of what the actual white point is. To quote from the ICC spec here:

Page 33:
"For displays, the values specified must be those of D50 normalized such that Y = 1,0 (i.e. 0,9642 1,0 0,8249)."

The actual white point of the display gets encoded into the "chad" chromatic adaptation matrix tag, and this is not something that you can easily reverse to see the value.

I believe there was a clarification on this issue by the ICC because early versions of the spec were open to interpretation that the actual white point of the display should be encoded into the "wtpt" tag.

If you want to find out what Photoshop is using for the white point of the display, you can always use the "Custom RGB..." trick. i.e.

1. In the Photoshop Color Settings dialog, *temporarily* select the "Monitor RGB - xxxxx" profile as your working RGB space.
2. Then select "Custom RGB..." in the list
3. The Custom RGB dialog should show the unadapted white point and chromaticities of the display.
4. Be sure to set your working RGB space back to whatever you were using previously.

Header white point is not D50?

At 10:15 AM -0800 12/16/03, Doug Walker wrote:

>While repairing Profiles with ColorSync Utility I notice many have the following notation:
>Header white point is not D50. Fixed.
>I should have only Verified, right? Before selectively repairing?
>Was this global repair not a wise and good thing to do if my workflow is 6500?

There are typically two white points specified in a profile.

The white point in the header refers to the white point of the Profile Connection Space (PCS). As the ICC has specified that the PCS white point is D50, then any profile that has a white point in the header other than D50 (or D50 encoded incorrectly) needs to be corrected - no questions asked.

The white point that a display may be calibrated to can obviously be different than D50. This is encoded in the 'wtpt' tag.

Now, in version 4 ICC profiles 'wtpt' tags need to be adapted to D50 so even a 6500K-calibrated display will have D50 in the 'wtpt' tag. This is going to cause some confusion.. Where should the calibration point of the display be recorded in the profile? in the viewing conditions tag. Whether or not this happens correctly in the future remains to be seen.

And yes, for those thinking this to the next step, Adobe RGB and sRGB should both have D50 as their 'wtpt' in v4 ICC profiles. Did I say confusion?


o Steve Upton CHROMiX
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
o ColorGear ColorThink ColorValet ColorSmarts ProfileCentral

MacBook Pro: Which LED display technology?


guillaume514 asked on Jan 7, 2012 3:41 PM:

Hi all, I'm trying to calibrate for photography my MacBook Pro 6,2 with a high-res matt screen using the i1 Display Pro calibrator.

The i1 software is asking me whether the technology used is CCFL (Cold-Cathode Fluorescent), Wide-Gamut CCFL, White LED or RGB LED.

From other threads, I'm pretty sure it's LED backlighting technology as the screen lights up immediately at start-up, unlike CCFL which apparently starts dimmer before brightening. So I've calibrated it twice entering once 'RGB LED' and once 'White LED' to see the difference. The 'RGB LED' calibration makes the greys look slightly cyan, and the 'White LED' makes the greys look pretty neutral, if not slightly red, but I'm still unsure which technology is used.

It would be very helpful is someone knew the answer and could help me out. Many thanks!!


Frank Caggiano replied on Jan 7, 2012 6:57 PM:

Open a terminal window and enter the following:

ioreg -lw0 | grep IODisplayEDID | sed "/[^<]*</s///" | xxd -p -r | strings -6

So on my 21.5 inch iMac I get this:

Pandora:~ frank$ ioreg -lw0 | grep IODisplayEDID | sed "/[^<]*</s///" | xxd -p -r | strings -6
Color LCD
Pandora:~ frank$

Google the model number and you'll get the manufacturers data sheet (as well as tons of other info).  For this iMac part of the spec sheet is:

So you can see the Lamp Type: WLED white LED


Tuesday, December 11, 2012

Monitor Profiling Tips;topic=58664.0

Title: Need help with ColorMunki Preferences on iMAC 27" CLUELESS HELP!
Post by: buckikiddies on October 17, 2011, 12:09:22 PM

I just upgraded my Spyder 3 Express to the new Xrite Colormunki. I am using the new 27" iMAC and I don't know if my monitor type should be RGB LED or White LED in the Advanced settings of the Colormunki. I am trying to get a lab print to monitor match and I'm not seeing it yet when I calibrate so I think something is off in my settings. There are three things I just need clarification on that I'm able to make a selection for within the Colormunki settings, if you are familiar with the iMAC screen please let me know what I should be choosing here:

White Point: Native or D65 (recommended setting)

White Luminance: use default or select my own cd/m2? (I can choose anything between 80 - 140 or Native)

Tone Response Curve: 1.8 or 2.2 (default)

Display Technology Type: White LED, RGB LED, CCFL, Wide Gamut CCFL

ICC Profile Version: Version 2 or 4

Any direction on which setting to use when profiling would be appreciated.


Title: Re: Need help with ColorMunki Preferences on iMAC 27" CLUELESS HELP!
Post by: shewhorn on October 21, 2011, 01:30:42 AM

In terms of Color Temp you can completely disregard what anyone tells you is "right". While the number may be ideal for a certain situation, your colorimeter may not be capable of hitting that target. If I calibrate and profile one of my screens to D65 using a Spectrophotometer and then measure the exact same spot with a Spyder 3 and a DTP-94, the numbers I get back are 7200ºK and 5600ºK respectively. Luminance is also all over the place. If the luminance is measured at 110 cd/m^2 with the spectro, the Spyder 3 will say 120 cd/m^2, the DTP94 agrees, and my i1 Display Pro tells me it's 96 cd/m^2. So, the instruments themselves can vary from unit to unit a great deal. Ethan Hansen has done some great work analyzing the consistency of the current tools on the market. You can read it here:

So, in addition to colorimeters being all over the place, you also have your illuminant to consider. If you proof with a 3500ºK bulb like John Paul Caponigro likes to do... D65 is most likely going to be way too cool. If your illuminant is D50 and you're looking at a traditional RA-4 print then D65 is what you want but the best way to get there is to use a known print and then adjust the white point until your screen matches paper white (same goes for luminance). Keep in mind that you might have an optimal luminance for proofing which might give you a headache when editing.

The best settings for white point and luminance are the settings that best match the conditions in your print viewing booth.

As for the other settings, type is white LED as mentioned. Set the gamma to 2.2. Again as mentioned, stick with the V2 profile.

Now... there's another HUGE part of this equation.

I am trying to get a lab print to monitor match and I'm not seeing it yet when I calibrate so I think something is off in my settings.

Your settings could be spot on, but unless you're using your lab's soft proofing profile in Photoshop, the print and the screen will never match. Photoshop needs to know how the output device (your printer) behaves so that it can make the appropriate adjustments to what you're seeing. There's a few settings in the soft proofing setup. One of them is "simulate paper color". It does a few things but one of the biggies is that it adjusts the contrast to match your paper's contrast. Your screen might have a contrast ratio of 500:1 or 600:1. Your print probably has a contrast ratio of 250:1 so you need to account for that when comparing a print to your screen. If you're just looking at the image straight up in PS you won't be seeing the changes that result from the printing process.

Cheers, Joe

Wednesday, December 5, 2012



Each is listed roughly in the order that they should be applied:

1. White Balance - temperature and tint adjustment sliders
2. Exposure - exposure compensation, highlight/shadow recovery
3. Noise Reduction - during RAW development or using external software
4. Lens Corrections - distortion, vignetting, chromatic aberrations
5. Detail - capture sharpening and local contrast enhancement
6. Contrast - black point, levels and curves tools
7. Framing - straighten and crop
8. Refinements - color adjustments and selective enhancements
9. Resizing - enlarge for a print or downsize for the web or email
10. Output Sharpening - customized for your subject matter and print/screen size

The above steps are virtually universal, so most photo editing software should work. If you've captured your images using the RAW file format (highly recommended), then the order of the above steps isn't as important, since they'll be intelligently applied when you develop using your RAW software. Otherwise it's critical that you follow the above sequence — especially with steps involving sharpening, resizing and noise reduction. Be careful though, extreme edits can easily cause image posterization with JPEG files.


Color Management is a chain — like all chains — it is only as strong as its weakest link.

At the end of the chain:

The printed print will match the 'calibrated' monitor — or — we missed something.

Finding that "something" should be no more difficult than reviewing the chain for its weak link….

Using Canon DPP software with Aperture

RAW is sensor data.  It does not contain any post-exposure adjustments or edits.  Any file that has any post-exposure edits or adjustments is not, and cannot be, RAW.

"DPP edited RAW files" simply cannot exist.  Once the RAW data has been converted to a viewable image file format, it is no longer RAW.  In order for you edits to these files to be saved, your software must create a new file.  This file cannot be RAW.

Every use of a RAW converter produces an image format file.  You select the image file format (e.g.: JPEG, TIFF).  These image-format files can contain edits and adjustments.  RAW files cannot.

A practical workflow using Aperture would be to use DPP for conversion and any edits you want to make, then export from DPP as 16-bit TIFF, and import the TIFFs into Aperture for storage and any other adjustments you want to make.  The path through DPP is one-way, though: after you have created the TIFFs, you can't go back to DPP and change them.

DPP writes the changes in the RAW file metadata. Because it's Canon's own software, it's the only one that can actually alter the metadata of the RAW file. Aperture stores edits in it's own database, as do all the other RAW converters (LR, DxO, etc.). For the other programs, you can export a sidecar file that contains the edits (altnough only the same software will be able to read the sidecar file).

Bottom line, you can safely edit the same RAW file with both DPP and Aperture, as many times as you want - each is independently nondestructive, and each will maintain it's own record of the edits, but neither will see the other's edits. If you want to successively edit the file with both programs while maintaining full bit depth, you'll need to convert it to a 16-bit TIFF image in one application, and import that into the other editor.

As I understand things, it's a mistake to think that you are ever actually editing the RAW file. A raw file does not contain an image, it contains camera sensor data that can be processed (rendered) to create an image.

A raw file contains an image just as does a TIFF. The raw image contains data in a mosiac format, whereas the TIFF uses a separate channel for each of the RGB components. Shown below is a straight dump of a raw image as shown by Rawnalize--it looks to me like an image. However, it needs to be demosiaced by a raw converter just as the three separate channels of a TIFF need to be combined in Photoshop.

DNG is rendered (demosaiced) data. So no, you are not sending the actual raw data from DxO to LR in the same way as simply using the original data (or converted DNG) in LR. Keep in mind that a DNG can contain rendered data. No different from a TIFF.

DNG files produced b DxO Optics Pro are not really Raw files as the ones that come out of the camera. First, they have been interpolated and demosaiced, since that's the only way for DxO to apply the optical corrections.

These DNGs still are not completely rendered files, that's why they open in ACR. Compared to Tiff's, they are not color space encoded nor gamma corrected.

However, those files have not been color space encoded. When you open them in LR/ACR, you could still select a camera profile and white balance as in a Raw file.

An important note is the way blown out highlights are treated when using this workflow: the resulting DNG don't have those highlight at saturation (equivalent to 255 in 8 bits) meaning that if you perform white balance in LR/ACR and then apply highlight recovery, your highlights may result non neutral. In this case you should perform white balance in DxO before producing the DNG.

Storing images as TIFF files is very space inefficient compared with raw, as TIFF images store three colours per pixel (at 8 or 16 bits per colour component, 24 or 48 total) compared to raw which just has the monochrome sensor data at 12 or 14 bits per pixel total. This monochrome data is interpolated into colour by exploiting the RGB colour filters placed in an alternating pattern over each pixel. To store the full range of colours available in the Raw you would need a 48bpp TIFF, which would take up about three times as much space (before compression).

Also raw preserves the maximum amount of editing flexibility - you're not commiting to any particular white balance or noise reduction setting. TIFFs are better than lossy JPEG images for archival purposes, but still not as good as raw.

I always keep the original Raw files, and keep a matching set of high quality JPEGs for easy viewing. There are arguments for using TIFF for archival purposes as it's an older, better documented format, understood by a much wider range of software. However if you're concerned about future compatibility then you can losslessly convert your proprietary Raw format images to Adobe Digital Negative files, which is an open format more likely to be supported in the future. The redundancy in an uncompressed 48bpp TIFF will make it slightly more tolerant of data errors, however. As Reid states there are better ways to guard against data loss, such as a backup system with error correcting codes, mirrored RAIDs etc.

I am now realizing the power of RAW for easy whitebalance and using Canon's DPP for DLO, and lens corrections. Also I do not want to spend hours working on RAW files and I like the "Canon Picture Styles" that come with DPP, which will likely be enough for 90% of my pictures.

So my question is, what and how should I manage my workflow?

I am thinking:

1. Copy RAW pics from SD to harddrive RAW directory;

2. Use DPP to sort through them and rate and discard;

3. The ones I keep, apply Canon Picture Style, work on whitebalance, sharpening, DLO, Lens correction etc. if needed;

4. Export all into TIFF to Aperture;

5. Do any further adjustments in Aperture if needed, including TOPAZ DeNoise plugin;

6. Export from Aperture as JPG into iPhoto;

7. Delete TIFF files from Aperture and re-import jpg into Aperture and organize (mainly to save space since TIFF files are huge).

(Yes this will work; the essential step is #4, making a tif, because, as you apparently realize, there is no other way to carry DPP edits over to Aperture. But perhaps you should reconsider whether you really need DPP. The only DPP editing that Aperture can't emulate or at least approximate is DLO which is a great tool but also has its downsides - it doubles the size of the CR2 file and, as said before, requires the creation of the tif. Personally, I have decided to forget about it for every shot except those destined for large prints where sharpness is more critical. I use LR, but like LR (and DPP, for that matter) Raw images edited entirely in Aperture do not need to be routinely converted to jpgs, only when one is needed for a specific purpose and it can be deleted afterwards.)

Tuesday, December 4, 2012

How to install ICC color printer profiles (Mac)

The ICC files must be placed in the proper folder for your software to see and use them.
Follow these steps and the restart Photoshop if you have it running.

Written instructions for Mac

Step One

Double click on the zipped file you downloaded from our site

Step Two

Copy and paste the profile (the colorful icon file) to the proper folder below.

Apple OS 10.4 and up - ICC File Folder Location

The standard location where you should copy and paste profiles -

Mac HD > Library > Colorsync > Profiles
If you do not see the profile available in Photoshop or other software try this location -

Mac HD > Library > Colorsync > Profiles > Profiles
If you encounter problems in color management or odd software behavior try putting profiles in this alternative location -

Users > "User Name" > Library > Colorsync > Profiles
10.7 Lion Special Notes

On a MAC running LION (10.7), the library/colorsync/profiles may be locked by default and can only be unlocked by an admin.  This state results in the inability of a user to install your icc print profiles per the normal instructions. Lion users may need to add unlock the profile folder in order to install printer profiles.

You must:

1. select the profile folder
2. select file/get info (top line menu bar)
3. click on unlock icon (bottom right of dialog box) and provide admin passwords
4. change folder access state to read and write.
5. click and drag (or copy and paste) the profile into the folder
6. reverse the process.

Any applications (such as Photoshop) that will use the profiles must be QUIT and restarted to see the new profiles.

Step 3

Restart Photoshop. The profiles will now be ready for use.