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Re: [OM] QP Card QP Color Correction Card (2 Cards) GQP201 - B&H Photo

Subject: Re: [OM] QP Card QP Color Correction Card (2 Cards) GQP201 - B&H Photo
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Tue, 19 Oct 2010 06:56:58 -0400
Everything I know I placed in my post below so I can't answer your 
question.  But I do agree that the original photographer (who knows what 
the image is supposed to look like) should do the conversion.  Only once 
have any of my photos ever gone to a 4-color press.  I did the CMYK 
conversion and they looked fine in print.

Chuck Norcutt


On 10/18/2010 9:19 PM, Bill Pearce wrote:
> OK, most all of my work is for 4-color press so let me ask some
> questions. I don't have such problems.
>
> I work in Adobe RGB. I have a LaCie monitor, and it is profiled not
> as often as the software wants. I prepare the files as usual, then do
> the cmyk conversion myself. Frequently, there is no difference in the
> appearance on my monitor. I tweek as required, and save it to a
> photoshop .eps file, at the suggestion of my printer. Almost all
> results are exceptional. It's easy and simple and even an idiot
> (myself) can do it. Does her printer wnato to do the conversions, or
> are they just masochists?
>
> Bill Pearce
>
> -----Original Message----- From: Chuck Norcutt
> [mailto:chucknorcutt@xxxxxxxxxxxxxxxx] Sent: Monday, October 18, 2010
> 7:10 PM To: Olympus Camera Discussion Subject: Re: [OM] QP Card QP
> Color Correction Card (2 Cards) GQP201 - B&H Photo
>
> It will take me a month of Sunday to digest all that but, in the
> interim...
>
> The QP target was recommended on another photography list in response
> to someone who was having difficulty getting proper CMYK conversions
> done by her publisher for shots taken in a particular area inside a
> large building.  Shots outside and inside elsewhere would convert
> OK. Strangely, the problematic shots (converted to ProPhoto in
> Lightroom) looked OK to her on her monitor but gave the publisher
> fits on the CMYK conversion.
>
> Because they looked OK to the photographer on a (presumably) sRGB
> monitor I wondered if there was some out of sRGB gamut (and therefore
> invisible to the photog on her monitor) discrepancies between
> ProPhoto and CMYK.  The person who responded with the QP target
> suggestion was obviously looking for a complex white balance
> solution.
>
> It might also be that the room in question has a combination of
> tungsten, halogen, fluorescent and sunlight and there's no simple
> solution.  I don't know what the actual lighting is.
>
> Chuck Norcutt
>
>
> On 10/18/2010 6:19 PM, Moose wrote:
>> On 10/15/2010 3:46 PM, Chuck Norcutt wrote:
>>> Anyone know anything about this?  I saw it mentioned on another
>>> list today.  It supposedly builds a custom profile rather than a
>>> simple white balance.
>>>
>>> <http://www.bhphotovideo.com/c/product/286652-REG/QP_Card_GQP201.html
>>>
>>>
#features>
>>
>> It looks to me like a variation on the ideas behind the ICC IT8
>> targets and ICC color profiles. In fact, Coca offers to build ICC
>> profiles from QP card shots. Whether the QP software builds ICC
>> format color profiles or it's own version, it is simply another of
>> several ways of mapping the results of image capture to a known
>> subject/source.
>>
>> For that use, I can't see where QP offers anything new, or
>> particularly useful:
>>
>> 1. QP targets - a. Cost $16.65 apiece, incl. shipping from B&H in
>> the US. b. Have 30 B&W and color reference patches on a 5.6 x 1.6"
>> (142 x 40mm) card c. Do not appear to have any reference between
>> their colors and correct colors. Either they have very special
>> printing technology or just don't care about that level of detail.
>> d. May require proprietary software to use, at least as intended.
>>
>> 2. IT8 targets: a. Cost $10 (or €10), incl. shipping (and get to me
>> quicker from Germany than ground shipping from NY) from Wolf
>> Faust. <http://www.targets.coloraid.de/> b. Have 228 color and 24
>> B&W reference patches on a 4x5" sheet of photographic paper. c.
>> Come with a standardized color reference file documenting the
>> differences between the target colors and correct colors and
>> readable by apps that create ICC profiles. d. Are an international
>> standard supported by many, many apps.
>>
>> I know which I would use. ;-)
>>
>> But let's back up a bit and look at the uses for such technology.
>>
>> 1. Correcting for inherent bias in an imaging system.
>>
>> This is the way in which I use ICC profiles. By profiling a
>> film/scanner combo, sensor system or sensor system and RAW
>> converter combo, I can correct for imperfections in their capture
>> of reflective color in images.
>>
>> Used this way in light other than that in which the profile was
>> made will show color differences from the same subject in the
>> reference lighting. This way, subjects shot in 'magic hour'
>> lighting looks like magic hour light shots, and so on.
>>
>> 2. Adjusting an image so that it appears to have been captured in
>> different light than was actually illuminating it.
>>
>> In this use, one may, for example, shoot in tungsten light,
>> including an image of the standard target in the same light, create
>> a profile and use that profile to correct color so the resultant
>> images appear to have been taken in daylight, with a highly color
>> accurate camera.
>>
>> This way, subjects shot in 'magic hour' lighting looks like they
>> were shot in midday light - except for the angle of the shadows,
>> etc.
>>
>> 3. One may combine the two basic techniques.
>>
>> For example, one may use a simple neutral reference item to correct
>> for difference from daylight in an image or set of images and a
>> color profile to correct for camera/film specific irregularities in
>> color response.
>>
>> So here comes the question. What do you want to do?
>> ===============================================
>>
>> Correct for camera/film inaccuracies?
>> -----------------------------------
>>
>> This is simple. Use an IT8 target and create ICC profiles to be
>> used in scanning or in post. It's the cheapest, simplest and most
>> accurate.
>>
>> Correct natural subjects? ----------------------------------- Most
>> of the time, I don't want to correct shots in other light to look
>> like midday light. I carry a WhiBal around in my camera bag, but
>> very seldom use it. Actually, I tend to forget it's there, but
>> that' at least in part because of my prior experience with it.
>>
>> To me, the problem is simple to state, somewhat trickier to deal
>> with. I shoot mostly outdoors, by natural light. Much of that
>> shooting is in light from various degrees of cloud/overcast, shade,
>> often colored by the foliage it has passed through and light from
>> open sky or sunlight at times other than midday.
>>
>> The result is colors that aren't correct, in the color profile
>> sense, but are perceptually correct. It's possible to correct a
>> shot of a color target shot in any of these lights to look just
>> like one shot in midday sun. But when I apply such correction to
>> shots of natural subjects, they end up looking unnatural.
>>
>> There are all sorts of clues other than color alone that let us
>> know in what kind of light a subject was shot. When a familiar
>> subject is color corrected to a light much different from that in
>> which is was captured, it tends to look "off", although it's often
>> hard to say exactly why.
>>
>> My experience with the WhiBal is that it tends to overcorrect, at
>> least perceptually, so the image is just wrong looking , to at
>> least some extent, in other than relatively ordinary, midday light.
>> When I have used it, I usually ended up applying it to a layer,
>> then adjusting the opacity to find a middle ground that looks
>> "right", like some combination of how I remember the scene and how
>> millions of other, similar, subjects have looked to me.
>>
>> Since I can do essentially the same thing with the WB sliders in
>> ACR, without taking extra shots with a reference item in the shot,
>> I don't find much need for the WhiBal.
>>
>> I've thought for a long time that Dpreview's endless rants against
>> Auto WB in tungsten light JPEGs from Canon cameras is misdirected.
>> I'm sure Canon is capable of making cameras that output "correct"
>> WB in incandescent light. So why don't they? I think the answer is
>> that their research has shown that most users don't like the look
>> of such shots fully corrected. We expect some shots to be warm, and
>> like it that way. Other visual, perceptual and memory clues let us
>> 'know' that daylight colors in those settings aren't right, aren't
>> what we saw.
>>
>> In summary, I just don't see the need for anything more
>> sophisticated than a neutral reference card or other gadget in any
>> but a few specific lighting situations.
>>
>> Correct studio work? -----------------------------------
>>
>> Not my area, portrait, product or what have you photography. Still,
>> I can't imagine the QP system can be as accurate as the ICC profile
>> system, nor is it likely to be as good as the Greytag/Macbeth
>> systems in use by so many pro studios.
>>
>> In Summary ===========
>>
>> I may be missing something, but I don't see where it offers
>> anything worthwhile that isn't already available cheaper and likely
>> more accurate. I can understand someone looking for a way to make
>> an honest bit of dosh, but I don't see where this product succeeds
>> in offering value.
>>
>> A. Critical Moose
>>
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