U of S | Mailing List Archive | alt-photo-process-l | Re: Three tricolor prints

Re: Three tricolor prints

Hi Katharine,

Just an idea and not so sure if its worth even trying out? If you were to take 3 of the seperation negatives and Gum print them individually on 3 different sets of your favourite paper. Then scan each gum print, you'd have to grey scale each one and then add each channel to a new photoshop RGB file. So what would turn out? A full colour image...though would it be anything like the original digital image from where it came, in regards with hue, saturation, colour, brightness, contrast? Would this be a tool in troubleshooting?
I know there is another mode in Photoshop, CMYK selective colour or MultiChannel, where you can set the colour channel to what you want, don't know if that helps?

Can I ask what your printing on (Transparency+Printer)? Also if you do muliple coats for each colour to build them up?


 On Wed Oct 17  1:44 , Katharine Thayer <kthayer@pacifier.com> sent:

>Hi Friends,
>A while back, I posted, just for fun, two tricolor prints as part of  
>my ongoing investigation of curves for gum; one of them didn't come  
>out well because as it turned out, the print settings were wrong and  
>the color applied to the negative was off.   I reprinted the  
>separations using the right print settings,  but haven't got around  
>to printing them on gum yet, although I'm looking forward to seeing  
>the corrected print.
>Instead of printing those separations, I printed separations from a  
>known image, the famous Adobe calibration image with Carmen Miranda  
>and fruit basket hat, to more clearly make my earlier point (quoted  
>at the bottom below)  that curves and calibrations should change only  
>the tonality of an image, not the hue ranges of the colors.  (And  
>perhaps also to make the point that there wasn't anything wrong in  
>general with my curves or with the method I use for generating  
>curves, as was suggested in that earlier discussion.)
>Just to make sure everyone understands, I'm just sharing work in  
>progress here;  I'm making no claims that these images are perfect;  
>either that the color balance is perfect or that the curves are  
>perfect, nor am I drawing any conclusions or asking anyone to draw  
>conclusions from them; they are just rough prints made very quickly  
>and not very carefully, to get a general idea of how these curves  
>"feel" to me.
>  In running test prints, I discovered that the pigment mixes that  
>had given me good tricolor prints with greyscale separations were too  
>concentrated for the colored and curved negatives, so I lightened the  
>mixes somewhat;  lightening them on the fly I didn't balance them  
>perfectly and will fix that before I print this pigment combination  
>again.  I'm finding that I don't like the PY97, ; I want a more  
>transparent yellow since my current practice involves printing yellow  
>last, and the PY97 leaves a film of opacity over the darker colors,  
>even though it's not a particularly opaque pigment as yellows go. So  
>I'll probably go back to PY110.
>I wouldn't make too much of small differences in colors that appear  
>in the different prints; this could be a result of inattention to  
>development times or to scanning inconsistencies, at any rate  
>shouldn't be taken as being an inherent  characteristics of  the  
>different types of curves.  And the curves are just as they came out  
>from ChartThrob, with minimal smoothing; I've done nothing yet toward  
>honing the curves to perfection.
>On Oct 5, 2007, at 9:10 AM, Katharine Thayer wrote:
>> A note re color balance:
>> Note that in these two prints, though the incorrect printer  
>> settings resulted in a print that seems to have a film over it, the  
>> actual colors are the same as in the print printed by the greyscale  
>> separations, simply muted because of the incorrect separations.     
>> The hues should not change;  if the pigments are correctly balanced  
>> in the first place, calibrations such as introducing a colorized  
>> negative, introducting correct curves,  and so forth should change  
>> only the tonal relationships, not the color balance.  If the color  
>> balance is off in the first place, it should be corrected by  
>> balancing the pigments, not by trying to correct the imbalance  
>> using curves.
>> kt
>>> On Sep 25, 2007, at 4:54 PM, Katharine Thayer wrote:
>>> http://www.pacifier.com/~kthayer/html/tricolorcomp.html