Old news paper pixel format???

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#1
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Hello guys.
I'm working on a project with the http://www.allelectronics.com/cg....
and a atmega.
This display only has one bit per pixel.
So i was thinking to put pics (wheater infromation of the net)
on this display like they did in the early days on newspaper.

Make a grayscale with black and with dots. Does any one know how you call this format. I try google but do not know how its call so can not find any infromation.

I know there are converters out there in the net, so any help will be good.

Many thans Pinkpanter

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It is called half-toning. Try searching Google with halftone

Hope this helps, Brenton

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thanks it is indeed what i'm looking for. Found a lib on sourceforge.org

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Glad to have been of help. The link could be Interesting, would you care to post it?

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The link is http://sourceforge.net/projects/... i must say i do not know for shure this is what i need but its a start.
But i think it is not avr friendly (memory part).
So i'm goning to halftone the pictures on a linux server (pentium 200 64 mb, how can linux work on this and windows 2003 server not hahaha)
and the atmel will grap it through ethernet and show it on the display when needed.

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For low-resolution displays, you rather need Floyd-Steinberg error distribution dithering. The algorithm is very simple and can be found on the net.
http://www.visgraf.impa.br/Courses/ip00/proj/Dithering1/floyd_steinberg_dithering.html
http://everything2.com/index.pl?node_id=465389

The Dark Boxes are coming.

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Heeeeee thanks man will look in to it.
Seems good
Pinkpanter

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BMP or TGA 1 bit per pixel, 320 x 240

Attachment(s): 

Go electric!
Happy electric car owner / builder

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I did a similar thing many years ago to get a "grayscale" out of a HP laserjet.

I did nothing complex. I decided that 13 levels of gray (including 0) were a sufficient tradeoff between resolution and shading.

I used a 4 x 3 block of pixels out of convenience. 4X4 could have been OK too.

I then developed by eye a method to fill the 4x3 bolck pixel by pixel to get a decent centered "dot" that slowly grows in size.

I had a look-up table for each raster row of dots for each shade I wanted to create. I did a simple average of all 12 pixels to generate the shade, then used the look-up table for the raster data.

Such a look-up table can probably fit in 18 bytes of ram. You can use high and low nibbles for separate entries in the table. 0 and 12 are easy and do not need a look-up.

This worked very well for me and the RAM & computation overhead was extremely manageable.

-Tony