2007.07.17 09:32 "Re: [Tiff] Re: Bit shifting and rotating of TIFF images", by Oliver Geisen
Simulated image of 16300x27501 pixels, bilevel:
* plain reading/writing (no bit-manipulation): 0.294 sec
using bit-shift operator ("<<" resp. ">>"): 1.920 sec *
using lookup-table: 0.380 sec*
> That is interesting. It seems that you are right that for the CPU
> you are using the lookup-table approach is much faster. Maybe it > is always faster.
I think this is true for images beyond a specific size (number of pixels).
>> How could an algorithm be faster?
> I am not sure.
When working with large images, i don't think any algorithm could beat this.
>> How is it done in assembler (my asm-knowledge is a bit rusty. It >> ends with Z80, which is about 20 years ago)?
> Sorry, I stopped with the 8085 myself. Over 20 years ago. :-) Okay, i think i'll stay at lookup-tables, because it's makes the best effort for me.
Kreisboten Verlag Mühlfellner KG
82362 Weilheim i. Ob.
Sitz Weilheim, AG München, HRA 64016, p.h.G.:
Kreisboten-Verlag Verwaltungsgesellschaft mbH,
Weilheim, AG München, HRB 119773,
Geschäftsführer: Dr. Dirk Ippen, Dr. Gerd Waldenmaier