Why is 100% not the darkest thing on the page?
May 2, 2008 9:25 AM Subscribe
What's the best way to get black levels to match between different elements in an Adobe Illustrator document?
I'm trying to help someone fix some issues with a poster she made for an upcoming scientific conference. She's having trouble getting all the blacks to print out equally black -- "black" black -- in her proofs. She has multiple RGB jpegs arranged within black rectangles. The jpegs are green monochromatic images created with a confocal microscope -- basically green "blobs" on a black background. The backgrounds of these images are printing out blacker than the 100% black rectangles. they are placed within.
We've tried the following without luck:
I'm trying to help someone fix some issues with a poster she made for an upcoming scientific conference. She's having trouble getting all the blacks to print out equally black -- "black" black -- in her proofs. She has multiple RGB jpegs arranged within black rectangles. The jpegs are green monochromatic images created with a confocal microscope -- basically green "blobs" on a black background. The backgrounds of these images are printing out blacker than the 100% black rectangles. they are placed within.
We've tried the following without luck:
- Converting the document's color space to RBG. This helps a little -- the contrast between the blacks is reduced but not eliminated.
- using the eye-dropper tool to pick the black background color from the jpeg and assign it to the rectangle.
- opening the jpegs in Photoshop and adjusting levels so that the black backgrounds are clipped to truly black.
Not sure if this is what you're after, but it sounds like you're trying to get "rich" black. Black produced using all inks will be darker than black produced with just the black ink. Try using a black that contains 100% of Red, Green, Blue, and Black. The additive properties of the inks will give you a deeper black than just 100% K.
On preview: what grouse said.
posted by medium format at 9:44 AM on May 2, 2008
On preview: what grouse said.
posted by medium format at 9:44 AM on May 2, 2008
I am more familiar with Photoshop but have done a little bit in Illustrator. If the jpegs are on top of the background, is their transparency set to something other than 0%, so that the rectangles and the images are being added together a little bit?
posted by TedW at 9:45 AM on May 2, 2008
posted by TedW at 9:45 AM on May 2, 2008
Response by poster: I will suggest the CMYK switch. Yes, the poster is destined for a CMYK HP DesignJet. The problem with having a whit background is that the images themselves are all different aspect ratios. Arranging them within a black rectangles makes for a cleaner look -- assuming we get it working.
posted by pmbuko at 9:46 AM on May 2, 2008
posted by pmbuko at 9:46 AM on May 2, 2008
You need to convert everything to CMYK, including the document colors and the photos. Anything else means unpredictable conversion on the fly.
posted by dosterm at 9:52 AM on May 2, 2008
posted by dosterm at 9:52 AM on May 2, 2008
Not all blacks are created equally. In printing, professional printers will frequently use rich black, which is actually a mixture of black plus the other inks to make it deeper and richer than just 100% black ink. As grouse and medium format said, that's the issue.
To get your blacks to match:
Probably the easiest thing would be to make sure your black swatch in Illustrator is rich black instead of 100% black. If you want the black in Illustrator to match the black in the images, open one of the images in Photoshop and use the eyedropper to take a sample of the black background. Double click on the color in your tools palette and write down the RGB or CMYK values of the black (depending on the colorspace of your Illustrator file). Then, go back to Illustrator and double click on the black swatch in your swatches palette, and enter those values.
Assuming all of your images use the same black background, that should get them all to match.
posted by MegoSteve at 10:10 AM on May 2, 2008
To get your blacks to match:
Probably the easiest thing would be to make sure your black swatch in Illustrator is rich black instead of 100% black. If you want the black in Illustrator to match the black in the images, open one of the images in Photoshop and use the eyedropper to take a sample of the black background. Double click on the color in your tools palette and write down the RGB or CMYK values of the black (depending on the colorspace of your Illustrator file). Then, go back to Illustrator and double click on the black swatch in your swatches palette, and enter those values.
Assuming all of your images use the same black background, that should get them all to match.
posted by MegoSteve at 10:10 AM on May 2, 2008
P.S. Merely taking an eyedropper sample of your placed JPEG from within Illustrator won't do the same as opening the file in Photoshop and taking a sample that way.
P.P.S. If you REALLY want to make sure they match, add the black border in Photoshop and then place the image with the border in Illustrator.
posted by MegoSteve at 10:12 AM on May 2, 2008
P.P.S. If you REALLY want to make sure they match, add the black border in Photoshop and then place the image with the border in Illustrator.
posted by MegoSteve at 10:12 AM on May 2, 2008
Best answer: If I understand correctly, the raster black (presumably a rich black) is sitting on a vector black (perhaps C0 M0 Y0 K100) and not matching. As already suggested, I would convert all images to CMYK, then eyedrop the black from Photoshop and use that rich black recipe (for example, C62 M70 Y50 K98) in the Illustrator document. The black recipe is likely to be different for each of the jpgs.
But if that doesn't work, I would try two things: 1. Resize the canvas of all raster images and fill the background with black to match the original black, and forget all about placing them on black rectangles in Illustrator. Do some masking/deleting/feathering/blurring to ensure that the background is seamless in Photoshop. 2. If there are too many images for that to be feasible, I would use an opacity mask in Illustrator to feather the edges of the placed jpgs so that they blend into their vector backgrounds more seamlessly.
posted by Uncle Glendinning at 10:13 AM on May 2, 2008
But if that doesn't work, I would try two things: 1. Resize the canvas of all raster images and fill the background with black to match the original black, and forget all about placing them on black rectangles in Illustrator. Do some masking/deleting/feathering/blurring to ensure that the background is seamless in Photoshop. 2. If there are too many images for that to be feasible, I would use an opacity mask in Illustrator to feather the edges of the placed jpgs so that they blend into their vector backgrounds more seamlessly.
posted by Uncle Glendinning at 10:13 AM on May 2, 2008
Response by poster: Thanks everyone. I've forwarded this page to the person working on the poster.
posted by pmbuko at 10:41 AM on May 2, 2008
posted by pmbuko at 10:41 AM on May 2, 2008
grouse, MegoSteve and Uncle Glendinning are exactly correct.
posted by lekvar at 12:04 PM on May 2, 2008
posted by lekvar at 12:04 PM on May 2, 2008
Response by poster: Just reporting back for closure. The poster came out well. Thanks again!
posted by pmbuko at 2:19 PM on May 2, 2008
posted by pmbuko at 2:19 PM on May 2, 2008
If you do make a rich black, avoid overloading the ink, for example 100% of all inks would be so much ink that it might have printing or drying problems. The maximum will vary depending on the paper and inks, but I'd avoid having more than 160% inkload generally, that might be something like 25C, 25M, 10Y, 100K.
posted by sycophant at 12:51 AM on May 3, 2008
posted by sycophant at 12:51 AM on May 3, 2008
This thread is closed to new comments.
No, you want to convert the photos to CMYK. Presumably you are printing this out on a CMYK device? The blacks in the photos might be converted to a rich black. There might also be color space issues that I don't even want to think about. Or there might just be some unevenness in how the ink is applied to the page.
Years of experience have taught me to use a white background for all my scientific stuff. Inevitably someone else will either forget to make something transparent, or make something transparent that should be white. When this happens it is ugly and unprofessional. Here, a colored background seems to be causing you other problems.
To cut the Gordian knot, consider using a colored or white keyline around the images. This will remove the contrast between the different colors of black.
posted by grouse at 9:43 AM on May 2, 2008