Britt’s advice re: the pen-and-ink drawings is right on the money. There is no need to keep them in CMYK. This just makes the files huge. Ultimately, they should be saved as pure black-and-white (1-bit-per-pixel or “bitmap”) TIFF files.

First, change from CMYK to RGB, then from RGB to to grayscale. But don’t immediately switch from grayscale to bitmap mode. There are a few things you should do first:

1. Save a copy of the grayscale files before converting to bitmap. As Britt mentioned, you’ll want to do any re-sizing on grayscale versions, so you should hang onto those just in case you need to resize them later.

2. On your working copies, go to the Image Menu > Adjustments and select Threshold. The image will appear to convert from grayscale to bitmap (i.e., to pure black and white pixels with no gray). In the Threshold dialog box, move the little slider to the left and right. You’ll notice that your ink lines become thicker or thinner depending on which way you move it. This is a handy tool to adjust the thickness of your lines so that dense areas of ink don’t “plug up” and thin lines and tiny stipple dots don’t get “blown out”. Once you’ve adjusted the image the way you want it, click OK.

3. After applying the Threshold adjustment, the image will appear to be a bitmap. However, technically it’s still a grayscale image. The final step is to convert the image to a true bitmap. Go to the Image Menu > Mode and change from Grayscale to Bitmap. In the Bitmap dialog box, be sure that the Input and Output Resolutions are the same and choose “50% Threshold” as the conversion method.

4. Save the image as a TIFF file.

Note: there’s also a “bitmap” file format (.BMP) but this is NOT the same as a bitmap mode image (1 bit per pixel). You should save the files in TIFF format, not in BMP format.  (Microsoft created this confusion by naming their proprietary raster format “bitmap” or .BMP, even thought the term bitmap, strictly speaking, should only apply to 1-bit-per-pixel black-and-white images).


From: Robert Golder <[log in to unmask]>
Reply-To: SciArt-L Discussion List-for Natural Science Illustration- <[log in to unmask]>
Date: Tue, 22 Dec 2009 10:34:13 -0500
To: "[log in to unmask]" <[log in to unmask]>
Conversation: [SCIART] Preparing color and B/W TIFFs for publication?
Subject: [SCIART] Preparing color and B/W TIFFs for publication?

I am seeking advice on preparing some scans for book publication.

Two years ago, I finished a group of 150 detailed illustrations for a book on fishes. All were done using traditional techniques, as specified by the client. Half of the illustrations were done in pen and ink, and half were painted in full color using acrylics. I scanned each artwork before delivery to the client, to have images to work with in case of loss or damage while the originals were held by the client or the printing company.

Not long after I had concluded my work (and gotten paid, thank goodness), the client ran into some problems. Difficulties with the first printer that was contracted to produce the book, and then budget cuts, forced the client to put the book project on hold. The client recently contacted me for assistance in finding alternative means to restart the process of getting the book printed and published.

One way that I can help is by providing my scans of the artwork. The color scans are 300 ppi CMYK-TIFFs and are color corrected the way I like them. The B/W line drawings are 1200 ppi TIFFs, and I think I made them CMYKs too (I still have to dig out the stored disks). I am particularly concerned about adjusting these B/W scans, as I recall that there are particular steps that ought to be taken to ensure smooth lines without "jaggies" and other issues that arise when preparing scans of line drawings.

Any advice on final adjustments to these color and B/W scans would be greatly appreciated. Many thanks ... Bob

Bob Golder
New Bedford, MA, USA

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