compression: strange precinct dimensions

[gcode-importer]

Originally reported on Google Code with ID 466

When compressing, precinct width and height for all resolutions except highest resolution
are set to half the value specified in command line.

This seems quite strange to me, particularly when certain specs such as DCP require
fixed precinct size of 256x256.

See this code in tcd.c :

if (resno == 0) {
    tlcbgxstart = l_tl_prc_x_start;
    tlcbgystart = l_tl_prc_y_start;
    /*brcbgxend = l_br_prc_x_end;*/
    /* brcbgyend = l_br_prc_y_end;*/
    cbgwidthexpn = l_pdx;
    cbgheightexpn = l_pdy;
    l_res->numbands = 1;
}
else {
    tlcbgxstart = opj_int_ceildivpow2(l_tl_prc_x_start, 1);
    tlcbgystart = opj_int_ceildivpow2(l_tl_prc_y_start, 1);
    /*brcbgxend = opj_int_ceildivpow2(l_br_prc_x_end, 1);*/
    /*brcbgyend = opj_int_ceildivpow2(l_br_prc_y_end, 1);*/
    cbgwidthexpn = l_pdx - 1;
    cbgheightexpn = l_pdy - 1;
    l_res->numbands = 3;
}

Reported by boxerab on 2014-12-25 14:46:50

[gcode-importer]

Bump.  

According to DCI spec:

Precinct sizes at all resolutions are set to be
256x256, except for the lowest frequency subband,
where a precinct size of 128x128 is used.

However, in OpenJPEG, all precincts are set to 128x128, as can be seen by code above.

Reported by boxerab on 2015-06-01 04:33:57

• Labels added: Priority-High
• Labels removed: Priority-Medium

[gcode-importer]

ok, my bad.  These are the dimensions for the band precincts, which are half the dimension
of the resolution precincts.   So, this is correct.

You may close this issue please.

Reported by boxerab on 2015-06-01 12:05:30

[gcode-importer]

Marking as invalid as per Aaron comment.

Reported by mayeut on 2015-06-01 16:03:45

• Status changed: Invalid