kodak colour patches

[ader]

Hi,

I'm a photography student and just trying to get a handle on the Kodak colour patches (swatches) that you put into your colour photos to assess the colour fidelity. I just want some info about what they do and how they can improve your colour fidelity...

thanks Ader

 

[docholliday]

I use a MacBeth color panel on the first frame of my studio work. That makes it a *known standard* for color, for product photography, I shoot a MacBeth as well as a grey step tablet. This way, since I know the colors of these items, I can calibrate my RA-4 process to produce final prints correctly.

Because a grey shirt with red pants can look like different colors of grey and red to one person, then different to another, the human eye cannot be considered accurate. The human eye adjusts to any given tone, a dirty white, if you stare at it long enough, will become pure white (at least that is what it seems like). So, you have to have a known standard to calibrate to. That's what the step tablet does. The MacBeth allows you to calibrate to a known cyan, magenta, yellow, grey, white, red, blue, green, etc.

Therefore, you take out almost all of the variance at the printing stage.

 

[Thilo Schmid]

Ader,

you will not be able to improve color fidelity in an analog process. It is determined by the materials you use and cannot be improved by alternate filter settings. But you may be able to choose different papers. Unfortunately, current color papers do not differ much in their color fidelity. Paradoxically, the interesting fields in the color patches are the gray (neutral) ones. They will give you a reference point for the correct filter settings.

 

[Ed Sukach]

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ Apr 24 2003, 12:28 AM)</td></tr><tr><td id='QUOTE'>Ader,

you will not be able to improve color fidelity in an analog process. It is determined by the materials you use and cannot be improved by alternate filter settings. But you may be able to choose different papers. Unfortunately, current color papers do not differ much in their color fidelity. Paradoxically, the interesting fields in the color patches are the gray (neutral) ones. They will give you a reference point for the correct filter settings.</td></tr></table><span class='postcolor'>
I think there must be some difference between "color balance" - "best fit filtration selection" - effected by producing an image on paper that agrees to the densities of cyan, yellow, magenta, and overall density - as the gray card.

What other characteritics do you consider to be "uncontrollable"?
Does this lack of control consder techniques such as "pre-flashing" to control contrast?

 

[vdonti]

Hi everyone,

My first post after a stint on another board that seems caught up in digital "I only change the same things just like you do in the darkroom" - yea, right.

I'm strickly anti-digital, so I thought I might be more at home here

On these color cards, help me out - never used them although I have a darkroom with twin D5XL enlargers and a 31" Kreonite processor on color.

Are you adding these color patches in one of your photographs and then adjusing your enlarger color Pack so the colors match? Just wondering if I need to get these?

 

[vdonti]

Also, Ed.

I did not understand what you meant with:

&gt;&gt;&gt;&gt;you will not be able to improve color fidelity in an analog process.&lt;&lt;&lt;&lt;

I do this all the time with my enlargers, so I must have misunderstood what you meant. It's been 33 years since I've been in Germany but, "Ich verstehe nicht" I think is how I said it?

 

[Ed Sukach]

On these color cards, help me out - never used them although I have a darkroom with twin D5XL enlargers and a 31" Kreonite processor on color.
Are you adding these color patches in one of your photographs and then adjusing your enlarger color Pack so the colors match? Just wondering if I need to get these?

I kind of "jumped in" and discussed one particular aspect ... that there are ways to control contrast, color balances ...

I use a ColorStar 3000 analyzer ... you may hear more about this machine on APUG in the future.

With this, I usually include the image of a gray card in one of the frames under a particular light. Gray consists of yellow, magenta, cyan (or, if you prefer, Red Blue and Green) and ~ 18% density.
From this gray card image, I'll make test strips, so that the analyzer, when calibrated (it has an internal calibration system) will duplicate that gray in the print.

It is entirely possible to calibrate this machine from a different color - I have a channel set up for "Fair Caucasian Skin" - or green grass, or blue sky..

It is not an infallible solution to all color balancing problems - the esthetic judgement takes precedence over the absolute values - but it is an *immense* help.

I know I've saved far more than the cost of this machine in materials, time, and frustration.

The MacBeth "Color Checker" cards are useful in comparing color balances between various films.... one can get an idea of the "strengths" and saturation of different colors -- "standardized" as "green grass", etc.
These puppies are realtively expensive - of late something like $70. The one I had was lost in the "great flood" that hit here a few years ago (12" of rain in 12 hours - my darkroom had three feet of water in it) and I haven't replaced it. I really don't miss it much.