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View Full Version : Total Ink Amount - help needed


real_ratibor
01-22-2007, 03:20 PM
Can anyone tell if there exists a plugin for Photoshop (or a method) that allow to locate or select pixels that exceed specified Total Ink Amount? I have to use Indesign for such operations but it is not a good idea as this method does not let locate such pixels precisely.

pgraham
01-22-2007, 09:58 PM
copy the channel for the ink you want to select, and use image/adjustments/threshold to choose your threshold ink amount. Then ctrl (or cmd) click on the threshold channel to make it a selection. Then inverse the selection, assuming you are in CMYK.

simmsimaging
01-23-2007, 03:18 AM
I am not aware of any plug-ins for that function, but it's pretty easy to do a quick scan across your shadow areas with the eyedropper and see what your total ink is at. If you have a problem you'll know quick enough - a few stray pixels over value won't make a difference.

I'm assuming you have your info palette set up to show total ink amount? If not you can go into the palette options on the flyout and select 'total ink' for the second color readout.

The quickest way to be sure is to just re-separate your file when finished working on it and tweak your blacks in the process.

b

real_ratibor
01-23-2007, 09:25 AM
No, that's not the way - I need select pixels thats have total ink higher than specified limit. For example, TIL is 300%, so, pixel 80/80/80/80 (c/m/y/k) is out of range and I want to have it selected. With your method if I use copy of cyan channel I may select 100/0/0/0 pixel that is within the specified range but I don't need it selected.
I tried to use tresholds of all channels to get selections intersection but it is not working the desired way.

Neil
01-24-2007, 01:59 AM
that's why adobe makes print software, it's easier with them to work with printing standards. The best option is to just adjust thresholds as stated, and eyedrop whatever looks like the darkest spots and adjust until it's under the threshold. You can tell what's darkest by blowing it out.

real_ratibor
01-24-2007, 02:03 PM
Does that mean that there is no way to do the same thing in Photoshop as InDesign does without boring searching with eyedropper over whole image?

Well, I'm afraid my English is not so perfect to be understood properly. I'll try one more time with illustrations:
http://img209.imageshack.us/img209/212/inklim13nw.th.jpg (http://img209.imageshack.us/my.php?image=inklim13nw.jpg)
the place in InDesign menus

http://img408.imageshack.us/img408/9595/inklim24yb.th.jpg (http://img408.imageshack.us/my.php?image=inklim24yb.jpg)
the result it produces (pixels exceeding 300% are marked red) and what I want to have in PhotoShop - precise location of pixels that are out of specified total ink limit in cmyk mode and alike selection.

Probably, I just don't get your point due to my weak English, but what I have with treshold for all channels (lvl 51 => about 100% to 80%):
http://img207.imageshack.us/img207/7927/channels5tk.th.jpg (http://img207.imageshack.us/my.php?image=channels5tk.jpg)
As you can see the resulting masks do not correspond with real wanted pixels distribution.

tfritzsche
01-26-2007, 12:59 PM
Hi real_ratibor
you can get close to what you want using Select->Color Range, dropper the darkest area and adjust your fuzziness. But correcting your out of ink limit areas this way can lead to loss of detail and solarization in your shadow/transition areas, The easiest way was suggested by simmsimaging, re-separate your image: Edit->convert to Profile (cs and earlier: Image->mode->convert to profle) choose custom cmyk, here in the States we would use SWOP inks, leave the dot gain alone, Black generation light, max black 80-90, and set the proper ink limit, in Russia I have no idea on the settings for ink set, but the rest is probably the same.

thomas

real_ratibor
01-26-2007, 05:11 PM
tfritzsche
Thnx, usually we do the same way using Eurostandard instead of SWOP but time to time it leads to undesired results - loss of color saturation in midtones (in all posiible variations of re-separations) so we have to be a bit tricky with images. Mostly these files are from Germany and GB, sometimes from America and have 340-360% of total inks. That's too much for most of local printing-houses. The problem pixels are very often located in nearly neutral areas so it would be great to adjust only these areas with selective colour or curves. The best solution is to re-separate image with printing-house profile but almost none of them offers such a service (at least those that chosen by our clients (big names, you now, can't tell, though, according to my contract)).

pgraham
02-05-2007, 02:10 PM
you'll have to blend your channels together before making the threshold.

copy each channel into a layer.
Set the bottom layer opacity to 100%, the second to 50, the third to 33.33, and the top to 25.

That will make each layer contribute 25% to the final image. The image then represents 25% of the actual ink that will be used (100% of the image means 400% ink). The threshold uses 256 to represent 100%, so you have to take 25% x 300% x 256 = 192 to get the threshold for 300% of ink.

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