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06/24/2006 12:37:51 PM · #1 |
Ok, I noticed the other day that Neat Image has two modes. Standard and Advanced... I've not been using it for very long, as you could imagine...
When in Advanced mode, I noticed that you could switch color space...
Now I played with this for a whole 20 seconds in PS 7.0 and I noticed some very subtle changes in the coloring that were more than a little hard to pinpoint exactly... It was different though...
Having heard a couple of things about using 'lab color' and how it can affect the color of the image negatively, I got a little worried and decided to keep my colorspace RGB for some time... I heard in passing in the Radiant Vista tutorials that CYK is often used for stuff that gets printed in magazines and other published works...
But here's the connection... It seems that Neat Image only uses CYK when in standard mode... I think I will probably be using standard mode for most stuff because it does seem to do a really nice job without worrying too much about it... I might also use it for batches...
It seems that I have a big batch job that needs doing in the next few days, so this is something of an interesting curiosity to me now...
Can anyone explain to me (and the general forum public) the differences between CYK and RGB color spaces and how an image might be affected by switching back and forth?
I usually export to 8 bit jpg's. |
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06/24/2006 12:46:25 PM · #2 |
where has my magenta gone?
drake |
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06/24/2006 12:54:41 PM · #3 |
It's CMYK
Cyan Magenta Yellow, Black (K). Don't ask me why black = k. :-)
The difference is that RGB renders the image by using 3 channels, Red, Green and Blue. While CMYK uses the above mentioned channels.
RGB doesn't work for screen printing and is why newspapers and magazines use CMYK. All web and electronic media work is done with RGB as well as anything sent to most Photo printers.
General there is no issue with switching back and forth between the two and not something you should really concern yourself with.
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06/24/2006 01:02:40 PM · #4 |
Originally posted by fotomann_forever:
It's CMYK
Cyan Magenta Yellow, Black (K). Don't ask me why black = k. :-)
General there is no issue with switching back and forth between the two and not something you should really concern yourself with. |
There is a major issue with switching back and forth, as the CMYK color space can represent only about 7000 colors, while normal 24-bit RGB color renders 16.7 million colors. There are a huge number of colors which will not render anything close to their RGB equivalent. Once you switch to CMYK, you will have compressed the color range dramatically. You can't really tell from the screen, because that's still an RGB process, trying to simulate what the CMYK output will look like.
The only reason to switch to the CMYK color space is if you are targeting a CMYK printing process, such as offset printing, and then you should always save a copy. Inkjet printers make the conversion on their own.
Black is referred-to by the letter "K" (last letter in the word) to avoid any possible confusion with Blue, which gets custody of the initial "B".
Message edited by author 2006-06-24 13:04:41. |
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06/24/2006 01:05:19 PM · #5 |
As Leroy is pointing out, CMYK is the "standard" color space for print media. This is because traditional, 4-color process printing uses 4 separate screens; one for cyan ink, one for magenta, one for yellow, and one for black. CMYK already has the "separations" coded into it. If you worked for a print shop preparing images for the press, you'd be changing the color space of every image to CMYK and creating separations in the computer.
The reason black is "K" is so it doesn't get confused with blue, as an abbreviation. It's "conventional notation".
R.
jejeje, the General_Music echo is especially strong today.
Message edited by author 2006-06-24 13:06:27.
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06/24/2006 01:16:28 PM · #6 |
Where I do use CMYK is in the Photoshop info window, where I display the colors as Grayscale on one side and CMYK on the other. I find it much more intuitive to visualize what color 50% Cyan, 40% Magenta, 5% Yellow, and 5% Black will combine to make up, compared to (say) Red 126, Green 241, and Blue 77. I think most people find it easier to predictably blend paints/pigments than colored light.
Also, when you see CMYK numbers in the Info window with exclamation points after them it means the color cannot be accurately rendered on a CMYK printer. |
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06/24/2006 01:49:24 PM · #7 |
Originally posted by GeneralE:
There is a major issue with switching back and forth, as the CMYK color space can represent only about 7000 colors, while normal 24-bit RGB color renders 16.7 million colors. There are a huge number of colors which will not render anything close to their RGB equivalent. Once you switch to CMYK, you will have compressed the color range dramatically. You can't really tell from the screen, because that's still an RGB process, trying to simulate what the CMYK output will look like.
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I stand corrected.
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06/24/2006 02:07:27 PM · #8 |
You may sit down now : )
I work in the prepress department of an offset print shop, so I have to deal with this all the time. Generally, it (CMYK) works quite well for photographic reproduction, where you have little bits of colors scattered throught the image area.
Where it really falls down is when you are trying to reproduce areas of solid colors in business graphics, especially if you are trying to match one of the standard Pantone color blends.
Try making a new RGB image and fill it with a vibrant purple* or rich red** or green*** color, and switch the color space back and forth between RGB and CMYK.
Try:
*R=0 / G=60 / B=212
**R=214 / G=0 / B=0
***R=46 / G=212 / B=0 |
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06/24/2006 02:52:20 PM · #9 |
I haven't worked much with pre-press or CMYK since college. Our front page for the college paper was often in color and was a pain in the hiney to layout.
Our process was to have Quark print out 10x14 (I believe that was the size) laser printer and paste (with wax) the sections onto large grid paper. Lining up was a pain in the rear even on the black only pages. But, lining up 4 seperate layers, one for each color, was a ROYAL pain.
The pages were then taken to the printer where he shot the pages onto screens and run it through the press.
Message edited by author 2006-06-24 14:53:25.
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06/24/2006 09:57:51 PM · #10 |
Right... CMYK... Sorry, it was quite late and I was pretty tired...
So here's the big question... if I run Neat Image in Standard mode (which apparently only uses CMYK) for batch, am I going to be cutting out a large range of color from my images? This step will be taking place immediately after RAW conversion and before any other measures...
I want to get it right as I have lots of pics to work on (abt 700) and not a lot of time (about 4 days in between my other schedule). |
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06/24/2006 10:13:30 PM · #11 |
Originally posted by eschelar:
... if I run Neat Image in Standard mode (which apparently only uses CMYK) for batch ... |
Are you sure -- that just sounds wacky. Why would any program dedicated to processing digital photographs work "only" in CMYK? One of the big differences between Photoshop and Elements is the ability of the former to work in the CMYK color space ... for that "professional" capability you pay hundreds more. |
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06/24/2006 11:16:14 PM · #12 |
RGB color space is additive (equal parts of Red, Green and Blue produce white on a monitor)
CMY color space is subtractive (equal parts of Cyan, Magenta and Yellow produce black - or actually a dingy brown in printing) The black is added to create a truer black.
You may notice in Photoshop that when you use color balance you have CMY on the left and RGB on the right. If you move a slider towards Cyan, you are actually red out of the image.
Another way to think about it is if you want a totally black area you will use 0 for each color in RGB or 100 for each color in CMY.
Most desktop printers have a conversion built into their driver to handle RGB images to convert them to CMYK for the print.
If you convert to CMYK in Photoshop, there are some settings that can be adjusted. That is why you see a difference when converting back and forth in PS. Most of those settings are for how the actuall offset printing press works such as dot gain and total ink limits, GCR/UCR and so on.
The other thing I noticed was the Neat Image is using YCbCr as the color space which is similar to RGB. It represents color as Y=brightness, Cb=Blue minus lightness and Cr=Red minus Lightness. I am not as familiar with this but it seems to be a close relative to RGB and not as much of a limiting connversion as say RGB to CMYK.
Hope this helps.
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06/25/2006 08:03:10 AM · #13 |
Thank you Igoofry...
I checked again and indeed, you are correct, NI does use YCbCr...
I thought it was similar to CMYK, just a different way of writing it...
Glad to hear that it's not as limiting... but I notice that in the advanced mode, there is a setting for RGB...
Does anyone have any idea why NI would not choose to use RGB as default?
And how then does YCbCr relate? Is it nondestructive in the back and forth process?
I haven't noticed that there has been any real loss in color when I actually do the NI step, so is it basically just in and out?
Thanks again, this is really useful info! |
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