Software suggestions for compressing a bitmap

[Hood]

Just tried but I think the greyscale looks better due to the colour change in the 16bit and the file size is the same with greyscale as it is with 16bit.

Happy now, thanks for all replies, now I just need to go and write some macros and alter the config files

 

[Hood]

Here are the comparisons

monochrome 19KB

16bit 77.4KB

Greyscale 77.4KB

The monochrome is no use and out of the other 2 I prefer the greyscale .

 

[eSCHEn]

You're all sorted now Hood but the reason why you see a basic bmp used for images rather than a jpeg or something lies in the complexity of implementing a decoder to change the image format back into a chunk of colour values. The BMP format is really, really simple to implement but JPEG, PNG, GIF etc are more work. When the machine is writing the bits out it will most likely do it from an uncompressed buffer and the BMP format is essentially this (but upside-down weirdly) so that'll be why they used it as well as it being a common format.

Four bits per pixel means you're getting two pixels per byte, which is about as good as you're going to get in an uncompressed format. You could do two bits per pixel but the image would be gash as you're only getting four values colours per pixel then.

Given the design of the image (lots of big chunks of same colour) then a simple RLE (run-length encoding) compression would reduce it a lot. However, I am pretty sure the device you're loading on to won't understand the format or even if it does it'll just decompress it back into a chunk of colour values again

GIF format, no dithering, no transparency and RLE enabled yields ~18Kb:

Do I get a prize?

 

[Hood]

....

Do I get a prize?

Aye it's waiting for you to collect from Fluffy's beard

 

[MCKDAVID]

inkscape? haven't tried it for bitmaps but seems to vectorise anything and then you can play around to suit size, and it's our favourite price.....

 

[eSCHEn]

inkscape? haven't tried it for bitmaps but seems to vectorise anything and then you can play around to suit size, and it's our favourite price.....

Vectorization would make those lines etc nice and small for storage as you're only needing the start, end and control points. As the image has lots of text in though you'd lose the benefit as those would either a) need to be converted to lines or b) left as text but then you need to install a font on the machine to render the text. The machine is very unlikely to support non-raster images though as they're more processor intensive than raster and that is a reduced-power device.