Virtual OS/2 International Consumer Education

September 1998

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Letters, Addendum, Errata

August 16, 1998 -
Just read your news, with the piece on clickware.

Thanks for the Plug...

Incidentally, we have another exciting project, we're taking on Spammers.


it's in dev at the moment ... not working yet.. but I'd like your comments

OS/2 Software @
We try to please

August 17, 1998 -

To whom it may concern.

I do have a prayer to all who write Websites.

In many cases it is necessary to keep a documentation for a given program to use it as a reference during installation. Often Websites contain important information that is written in HTML that wastes half a sheet of paper.

I usually print such information on my black and white Canon printer, and find many websites are written with large areas of background or border frames that print all in black on the inkjet machine. This is waste of costly ink.

Johannes Lomholt

August 31, 1998 - The following letter is in response to Don Eitner's review of the Lexmark Color Inkjet 5700 printer in the August VOICE Newsletter.

There are six different colors that can print in each printed pixel, three from each cartridge. And, they can overprint each other, so we can't just use three bits and say "print color 0, or color 1, or ... color 5". We need six bits for each pixel so we can use any combination of those six colors. I generalized to one byte (eight bits) because that's what a hardware designer would typically do. Then, in the firmware, for each nozzle the firmware can just scan that particular bit of the appropriate byte and decide whether or not to print its color.

That's why it should only be one byte per pixel, not three. I explained that when scanning you'd need three bytes for 24-bit color, but when printing you only have 64 possible colors: each color can be on or off (you can't control the size of the ink drop), so you have 2^6 possible colors, or 64 possible colors. It's dithering that gives you the gradients, and a higher dpi gives you a less-obvious dither so the image looks better.

There are only six nozzles per printed pixel. There are more nozzles on the ink cartridge, of course, but they don't overlap. Each nozzle is dedicated to a certain subset of the printed pixels. That speeds up the printing (you could make an ink cartridge with only one nozzle, but then you could only advance the paper 1/1200" on each pass, and it would print very slowly).

You say it's a CMY (actually, CMYK since black is stripped out) image going to the printer. I don't think so; as I said, that eliminates many of your screening options and only allows what's in the firmware. And that's unlikely, since then you couldn't do smooth curves (such as when drawing a circle) because the circle would be screened. The firmware has to allow for nozzle control.

Take another think on this. The translation must be done in the software driver. Three bytes for the image pixel become one byte for the printed pixel. Only in a thermal transfer printer, where each printed dot can be made any size you want (by changing the heat), would you have three bytes per printed pixel.

Your tremendous swap file might have been caused (I'm guessing here) by the translation of the source image size, not by its color depth. For example, if an image that's 2500 pixels wide must be printed on a page in a rectangle that's 3333 pixels wide then there's a lot of interpolation that must be done. The interpolation uses a lot of memory, but that's not a printer driver problem because if the image is the correct pixel size to begin with then no interpolation is required.

Of course, the printer driver could have some poor coding in it, such as using 32-bit values to hold the 6 bits for each "printed pixel". If you have an information file for the Lexmark with its printer command set, I could take a look at it and see exactly what the format is for its input files (PCL is in hexadecimal character, which doubles the file size right there).

Certainly, if I'm wrong please correct me. I'm always trying to learn, and I like to ask questions.

- Peter Skye (

Reply from Don Eitner, the author of the review of the Lexmark Color Inkjet 5700 printer

The Editors of the VOICE Newsletter would like to thank Mr. Skye for his contribution to making the VOICE Newsletter as accurate as possible. We appreciate the efforts of OS/2 users who are active in their support. Peter Skye is a frequent contributor to the SCOUG web site ( including his most recent article "A Future Vision Warpstock is the Tomorrow of OS/2" -

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