teeuwen
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Posts posted by teeuwen
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<p>Off-topic, but I just noticed that Steinmueller released a free script called "DOP Split Bright Dark".<br>
The script splits a layer into a brighten and darken component. A companion to his commercial script "EasyDS Detail Sharpness Resolver", but it can be used with other sharpening/local contrast enhancement filters to control light and dark halos.<br>
<a href="http://www.outbackphoto.com/index_news.html">Link</a></p>
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<p>Did you try the demo James (works on images up to 2000 pixesl)?</p>
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<p>My favorite method, Uwe Steinmueller's "B&W Resolver" script. All the control you need, <a href="http://www.outbackphoto.com/CONTENT_2007_01/section_workflow_basics/20090118_DOP_BW_Resolver/index.html">link</a></p>
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<p>> I've always seen that it's recommended to turn it on.<br>
From Adobe:<br />"Color conversion using Perceptual intent already maps source white to destination white and source black to destination black. Because this mapping preserves the relationships of the shades, it is unlikely that a whole shadow section will be mapped to the same black value. Therefore, BPC should not be necessary. BPC is available, however, for this rendering intent, to be used with malformed profiles. For a given picture, the user can decide whether using BPC improves the color conversion and can select it or deselect it accordingly.<br />BPC is available for color conversion using the Saturation intent. As with Perceptual intent, the user may or may not find that selecting BPC improves the conversion of a given image."<br /> <br />h**p://www.color.org/AdobeBPC.pdf<br /> <br />See also Eric Chan's (Adobe engineer) pages on the 3800 and especially his "Epson 3800 ICC Profiles for the Advanced B&W Photo Driver"<br /> <br />h**p://people.csail.mit.edu/ericchan/ <br /> </p>
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<p>> the Optix is a superb but discontinued product.</p>
<p>Is it really discontinued Andrew? <br />See e.g. <a href="http://www.integrated-color.com/cedpro/dtp94.html">http://www.integrated-color.com/cedpro/dtp94.html</a></p>
<p>- In Europe, EIZO now bundles their CG displays with the DTP94<br />- QUATTO supplies it with their high-end displays<br />- It's still bundled with ColorEyes Display</p>
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I also use both packages. I basically agree with Andrew, but I would love to see MonacoProfilers's perceptual algorithm incorporated into ProfileMaker (additionally), since IMO MonacoProfiler creates a far better perceptual rendering intent.
I find the difference especially notable on photographic printers.
I used to recommend MonacoProfiler to photo labs, but nowadays I suggest that they go for Barbieri hardware/software (if the are willing to pay the extra money).
The Barbieri software creates the best perceptual intent I've ever seen. Extremely close to colorimetric, but without the clipping.
A number of my photo lab clients run automated processes and convert everything that does not have their standard profile embedded, into their printer profile using perceptual intent. Hence the importance of a good perceptual intent.
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> Is there some tables also to get the proper values according to the color space i'm using: Abode 1998, ProPhoto...
See:
http://www.babelcolor.com/download/RGB%20Coordinates%20of%20the%20Macbeth%20ColorChecker.pdf
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> Also, how do monitors do display large gamuts? Do they use perceptual or relative?
Depends on the display profile type: Matrix > Colorimetric ; LUT > Perceptual or colorimetric
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> On the whole, you get a more accurate reading with a spectrophotometer
Mr. Lang (Sony Artisan, Radius PressView etc.) obviously doesn't share your opinion.
From above referenced article:
"The 1nm Metrology Lab Spectroradiometer ($40,000-$100,000)
If budget and time are not factors you care about, this is the very best way to measure any emissive color. I am often confronted by persons who attempt to convince me that a spectral device is the best way to measure a display's color. If this is the device they are referring to, they're right, however at a reasonable price point for the purpose of calibration they are wrong."
"For a job like measuring a white light source a low end spectral device may be excellent. If you are adjusting the grey tracking of an LCD display, the error of the device on the darker patches may be far greater than the adjustment accuracy of the display.
My experience has shown that to accurately calibrate a display with a spectroradiometer you need to spend at least $10,000 on the device."
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> The next (big) step up from the Spyder is a pro model which measures both emitted light (monitors and projectors) and reflected light (prints).
A colorimeter is generally a better instrument for calibrating displays than a spectro. A spectro like the EyeOne Pro is far less accurate in measuring colors at lower luminance levels.
See for example this excellent article from Karl Lang:
http://www.lumita.com/site_media/work/whitepapers/files/xrite-wp-3-comments.pdf
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> The only way to tell if it is any good is to compare it with a reference device.
Right, and we haven't seen that (yet).
> I understand the benefit of having a higher number of filters (it's to better approximate the color matching functions), but not of the larger apertures.
The larger aperture is undoubtedly an avantage because of the higher signal to noise ratio.
On the wide gamut issue, the real high-end displays (like the LEDs) come with custom colorimeters.
These custom (mostly OEMed) colorimeters are calibrated to this specific wide-gamut device through a custom calibration (correction) matrix.
Other high-end displays like for example the EIZO CG241W that I'm using, supports standard all-purpose colorimeters but EIZO's ColorNavigator software includes the correction matrixes that are needed to calibrate a specific colorimeter to a specific display. That way, the DTP94 that I'm using is also optimzed for my wide gamut CG241W.
A good read on the subject: http://www.lumita.com/site_media/work/whitepapers/files/xrite-wp-3-comments.pdf
And here's a quote from Peter Karp from Quato, originally posted on Apple COlorSync:
"> What is the purpose of your correction matrix? You use top-of-the-line instruments to correct the display relative to what?
We use the Minoltas to create a calibration matrix for the
colorimeters for a _specific_ display model. Especially the DTP94 we
still bundle with our displays will need/benefit from a custom
calibration to a specific display model.
A perfect colorimeter would simulate the response of our eye (CIE 1931
standard observer color matching function to be more specific)
perfectly. Real world colorimeters will not reach this goal totally --
one exception for example is the colorimeter from LMT, Berlin which
uses many tiny filter elements to match the CMFs very close. Low-Cost
colorimeters will have filters which will not match the CMFs. The
subject of building measuring devices for "color" is very interesting
and challenging.
So most colorimeters for desktop usage like the ones used in our
industries must be calibrated to a specific device. _Then_ and only
then the measurements will be very accurate. For other devices the
measurement accuracy will be worse. Because the monitor is not known
at first hand the manufacturer has to choose some sample monitors and
create an average calibration which matches the average of the sample
monitors -- therefore you'll get "average accuracy" on your average
display. The accuracy will be improved much, when the specific device
is known and is used for the calibration of the device.
Those facts are the reason why you need to choose "CRT" vs. "LCD" in
several monitor calibration packages. One setting will load the
calibration for an average CRT and the other for an "average LCD".
For CRTs the calibration was fairly accurate because most CRTs had a
similar gamut, but for LCDs the differences are much broader --
threngthening the need/benefits of a custom calibration.
Best regards
Peter Karp"
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> It has been optimized for wide gamut displays with the addition of a larger sensor
Gerald,
Can you tell me where you got this information that the Spyder3 is optimized for wide gamut displays?
AFAIK, none of the current 'standard' colorimeters is optimzed for these wide gamut displays. There is a reason that the real wide gamut LED diplays (like the NEC SpectraView LED, Samsung XL series) come with custom colorimeters including filters mated to the display.
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> Printer profiles are made for perceptual rendering by default.
Please explain?
> ... make sure that the out of gamut colors are brought within gamut
The essence of perceptual gamut mapping is (fixed) gamut compression of ALL colors (out-of-gamut + in-gamut).
So why bother bringing out-of-gamut colors within gamut when using perceptual?
> Relative rendering should be used for converting from one color space to another
Relative colorimetric is the ONLY intent that will be applied when doing working space (matrix) conversions.
It's not the only option you have in PS, perceptual is not grayed out, but PS WILL do a relative conversion.
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> 2_yes in both case. or i should say always if you can.
The majority of the paper profiles incorporate a perceptual rendering intent that tries to make use of the whole dark range of the media, by definition.
Therefore, since it already maps the dark colors of the media,
enabling BPC does not affect this rendering intent much... almost always.
Quote from "Adobe Systems' Implementation of BPC"
http://partners.adobe.com/public/developer/en/pdf/AdobeBPC.pdf
"Color conversion using Perceptual intent already maps source white to destination white and source black to destination black. Because this mapping preserves the relationships of the shades, it is unlikely that a whole shadow section will be mapped to the same black value. Therefore, BPC should not be necessary. BPC is available, however, for this rendering intent, to be used with malformed profiles. For a given picture, the user can decide whether using BPC improves the color conversion and can select it or deselect it accordingly."
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> but that's not what it's doing (it doesn't follow the gamma formula).
See "Note on Photoshop Gamma" on pages 18 and 19 of David Dunthorn's "Maintaining Color Integrity in Digital Photography":
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> and did not find anything that it could do that regular photoshop CS3 could not do.
Output specific sharpening (based on empirical data) maybe ?
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The behavior of the middle slider in the levels dialog is inversed.
To apply 'gamma encoding/correction' to a linear file you should use the inverse of gamma 2.2 being 1/2.2=0.45. As the scale in levels dialog is inversed you should use 2.2
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> Can someone tell me about/ send me a link to some simple explanations of Light Jet Printing?
for more info on
Oc頌ightJet 430
Oc頌ightJet 500XL
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Yes, always leave images in their working space while soft proofing / editing. Printer profiles are bad editing spaces, because they lack the properties of working spaces (like sRGB, aRGB etc.), that are more or less perceptually uniform and gray balanced.
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> are there any benefits to using newer colorimeters
IMO NO, it's a very good instrument. Use it with ColorEyes display.
A quote from the guys from Chromix in their latest newsletter:
- The Monaco Optix XR colorimeter (also known as the X-Rite
DTP-94) is being discontinued by X-Rite but, ironically, is
considered the best colorimeter out there. Statistically it is very
accurate, very repeatable, and has a number of more elaborate
circuitry features such as automatically adjusting for ambient
temperature changes. We have hoarded some of these at CHROMiX. Call
our sales department if you are interested.
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> but they all use the same process
Yes, mainly digital presses from HP and Xerox.
> higher end printing...
BTW, there's a huge PDF (65 MB ! ) on Bill Atkinson's website 'showing' the making of his book "Within the Stone".
Recommendations for Color Management
in The Digital Darkroom: Process, Technique & Printing
Posted