Legacy ImageMagick Discussions Archive

Dear Reader,

Here I'm trying to find out some charactaristics of jpeg2000 en/decoder: Lurawave JP2 Plugin for Irfanview, Kakadu (current version), Openjpeg 2.1.0.

Here my test image (somewhat synthetic, with small @ with different contrasts):



Target size: 64600 bytes.

Here the difference of the results


Below red line: lurawave
below green line: kakadu
below blue line: openjpeg

Discussion:
Lurawave: Some darker @ symbols are visible, meaning that some @ with low contrast vanished. Color constancy is good.
Kakadu: A lot of high-frequency noise - unusable for text scans; very good color constancy.
Openjpeg2.1: No @ symbols lost - color constancy comparable to lurawave, but somewhat more coarse.

I'm wondering where the significant color differences are (see thread "better quantization tables")

Kind regards...

Well, now somewhat more psychedelic:

Original (some dots with pixel text of varying contrast):



Target size: 23040 bytes (1/40).

Lurawave JP2 Irfanview:


Kakadu 7.4 with -precise:


Openjpeg2.1:


And here the optically enhanced difference
below red line = lurawave
below green line = kakadu
below blue line = openjpeg2.1


Openjpeg: large color shift at borders, but sharp text.
Kakadu: noisy Text.
Lurawave: something between.