if use c44 - add --crcb options

[jwilk]

Issue reported by mivan748 at Google Code:

-crcbnormal -crcbhalf -crcbdelay n -crcbfull -crcbnormal and -crcbdelay 0. -crcbnone

may be useful to get higher image quality sometimes your pdf2djvu produces awful images

[jwilk]

Comment submitted by mivan748 at Google Code:

and comment - what crcb opt uses your pdf2djvu

[jwilk]

pdf2djvu uses c44 only in very exceptional situations: to create a solid-color (non-white) background. It doesn't call it with any --crcb* options, so the default --crcbnormal is being used.

In all other cases, pdf2djvu uses csepdjvu to create IW44 layers, which doesn't have any options to control resolution of chrominance encoding.

[jwilk]

Comment submitted by mivan748 at Google Code:

i convert pdf with raster images and c44 opts has great effect on img quality images was lowcolor (32color) and it was hard to obtain acceptable quality with same size so the idea is to code such pdf with lowcolor opts of c44 to reach high compression with same quality. present 0.7.14 codes such images in excessible sized iw44 chunks... why crcb opts omitted? it can be helpful...

[jwilk]

Comment submitted by mivan748 at Google Code:

--bg-subsample=n
Specifies the background subsampling ratio. The default is 3. Valid values are integers
between 1 and 12, inclusive

so that option provided by what?

question created by wierd results - screenshots good compressed with 300-1000% increased file size...