Q: Printing 1-bit image dot by dot w/o halftoning

[Oh-Yeah?]

Hi,

I'm trying to print a computer-generated hologram, which requires a high resolution.

I want to print the 1-bit (binary B/W) image exactly as is, at either 1200dpi (laser) or 2400dpi (inkjet) etc.

But I came to learn that, nowadays, most printers do not allow us to print directly at their max dpi; for example, when I send a bitmap (or PDF etc) to a Windows printer driver, it automatically lowers the dpi so that it can use some dot-patterns for halftoning. Many drivers do not even indicate the actual dpi at work, but just say "best quality" etc.

So here's my newbie question: how do I tell my printer like "Just print these dots at your max dpi; don't bother with halftoning or dithering" ?

Right now I'm trying GIMP + wingp (gutenprint for win), but I'm not yet sure how to define my printer settings (PS, PCL6, Epson, or Canon, etc), and I'm not sure if it's possible at all to do such a job with this software combination.

Maybe (I imagine) I might be able to write PS or PDF or PCL6 scripts to embed the image data for direct printing?

I'd appreciate any help. Cheeeeeeeers

P.S. I know there are professional "image setter" services out there, but I hope to see how far I can go with ordinary printers around. Thanks!

 

[The Hat]

Hi @Oh-Yeah and welcome, maybe you’re looking at your printing issue the wrong way round, you could try using a postscript laser printer, they can control dpi far better than a bitmap printer can..

 

[Ink stained Fingers]

you cannot bypass that halftoning in the driver/firmware, an inkjet printer prints with a physical resolution of 600/720dpi - Canon /Epson, and all the promised 2400/4800/5760/9600 dpi is related to the dithering within every image dot for which the color is rendered in a 4x4 or 4x8 etc layout, possibly with some multiple overprint and different droplet sizes depending on your printer. I have not seen any software which bypasses all that and let you address those 'subpixels' in an image dot directly. You probably would have to hack the printer firmware to get there. I don't know what and whether other professional equipment is available to print with such resolution - e.g. direct laser onto film or printing with a larger scale and scaling down photographically onto sheet film

 

[Oh-Yeah?]

Thanks a bunch for quick replies!

@The Hat:
Thanks for your suggestion. Actually my Minolta is supposed to accept PS, but I am not sure -- if I send it PS commands that embed a 1-bit image @ the highest dpi, does it really do the job honestly, or do the automatic halftoning (which I want to avoid)?
Anyway, I'll google and learn how to embed 1-bit data in PS. (My knowledge of PS is super-slim; I only know its manual is a huge phonebook

@Ink stained Fingers:
That's a valuable advice. Just a thought -- if I can tell the inkjet driver to turn off the tweaking (overprint and different droplet sizes etc) somehow, and if I know how to choose a specific dot pattern among all possible ones (2^16 patterns for 4x4 case), then, in principle, I can do what I want by dividing my image into subcells and print each cell as a 4x4 pattern.
In fact, such a method is perfectly suitable for a classic algorithm of binary hologram (Brown-Lohmann-Paris), where each of such cells encodes the intensity and phase of light.
But -- dream is just a dream. Hacking the firmware would be out of my hand. Is there any information available, on controlling Canon or Epson printers at such a raw (low) level? Good printmen's hacking guide or something?

 

[turbguy]

Be aware that printer OEM`s quote a cerajn dpi, but if you have say a 6color printer, that 2400 dpi spec may be 600 dpi OF EACH COLOR!

 

[Ink stained Fingers]

I'm not aware of any way to access the dots on a subpixel level, not even with the typical RIPs used for large format printers and which replace the regular printer drivers. It is even more difficult, assume you print a light gray area, every pixel is made of 2 out of 16 possible subpixels, the firmware/driver is randomly distributing those dots within every cell so that you wouldn't recognize a regular pattern, horzontal or vertical fine lines , but a rather smooth and lightly toned gray area. You are feeding RGB (or CMY) data at the image pixel level to your driver, or RIP, and how they translate that into the control of individual ink shots that is not accessible for the user. Some RIP software offers the choice of different dithering algorithms but no direct access to the ink shots.

 

[Oh-Yeah?]

@turbguy :
@Ink stained Fingers :
Thanks! Well, it's too bad to know the "reality-bites" facts. But it's still good for me that I've learned these BEFORE I start a huge investment of my time and effort into it. It would've been too painful to find myself, after months, shouting like "No way!!! AAAAAHHHHH!!!!"