Thursday, April 08, 2010

Collapsing the hard disk requirements of Slice and Dice



I managed this by the simple expedient, suggested by my son Adriaan, of replacing the BMP format slice image files with the Portable Network Graphics (PNG) format which uses a lossless data compression scheme.  This reduced my slice image files in size from 16-22 Mbytes per slice to 80-100 Kbytes.

5 comments:

dissidence said...

thats great news i think, i wonder if it will help lesson the cpu load too.?

Prober said...

I believe your on the right path, but before you lock things in take a look see at the IFF format.
http://en.wikipedia.org/wiki/Interchange_File_Format .

It might not get you the size reductions you looking for; however IFF is very powerful with features of "numerical data, text, or raw data".

Might be possible to "Embed" Reprap controls (temp etc.) into the file and make a "wrapper" out of the current setup?

Forrest Higgs said...

dissidence: Nope. The slice images are just as complex, but more efficiently stored. :-(

Prober: I'll certainly take a look.

pelrun said...

There's no need to move away from PNG, as it supports arbitrary chunk data as well. Mark a chunk as ancilliary, and any app that doesn't understand it will just safely ignore it.

Prober said...

@pelrun: Why go for a copy when you can have the real thing?

“and the PNG specification has imitated loosely some of the concepts. (One major change is that PNG files are designed to be easily serially writeable. IFF writers generally rely on the ability to seek back and update data.)”

http://www.ibm.com/developerworks/power/library/pa-spec16/