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Grayscale

GDS_RIP can be customized to produce grayscale output. Contact Artwork for this feature.


BMP - Grayscale Details

To implement BMP in gray scale requires that one use the indexed color option. A table of 256 "colors" is included in the BMP file header. Each pixel entry consists of one byte - the value of the byte is a pointer into the table.

Below you can see graphically Artwork's color table for gray scale BMP.




and here is the actual data in the BMP file header:

0: 255 255 255   0
1: 254 254 254   0
2: 253 253 253   0
3: 252 252 252   0
4: 251 251 251   0
5: 250 250 250   0
6: 249 249 249   0
7: 248 248 248   0
.
.
.
249:   6   6   6   0
250:   5   5   5   0
251:   4   4   4   0
252:   3   3   3   0
253:   2   2   2   0
254:   1   1   1   0
255:   0   0   0   0

Super Sampling vs. Gray Levels

The number of gray levels we generate will be a function of our super sample settings. GDS_RIP has several levels of super sampling:

SupersampleGray Levels
24
416
864
16256

Example of Super 2 Sampling

Below you can see some parallel lines that have been rasterized at 101,600 DPI with super-2 sampling. The resulting gray scale image is 50,800 DPI and has 4 total levels of gray: 0,63,191,255


Each pixel is represented by one byte. The value in the byte points into the color table found in the BMP header.



Example of Super 4 Sampling

In super 4 sampling we first rasterize at 203,200 (4 x the desired 50,800 DPI) and then convert each 4x4 array of monochrome pixels into a gray pixel. This does not change the BMP in any way except that we now have more levels to choose from:



Sample Data

Below you can find two small sample files.

super2_101600.zip 50,400 DPI, Super Sampling=2, 745KB zipped; 43,630KB unzipped

super4_203200.zip 50,400 DPI, Super Sampling=4, 834KB zipped; 43,630KB unzipped




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417 Ingalls St.,     Santa Cruz, CA 95060         Tel (831) 426-6163     Fax 426-2824               email: info@artwork.com