[argyllcms] cctiff dither feature request
- From: Nikolay Pokhilchenko <nikolay_po@xxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 06 Feb 2014 13:09:18 +0400
6 Feb 2014, 12:58 +04:00 Nikolay Pokhilchenko wrote:
>6 Feb. 2014, 0:16 +01:00 mbielowicz wrote:
>>Let there be a workflow (without native calibration capabilities):
>
>An advice: do not use 8 bit per channel bitmaps nor for profiling nor for
>production printing if the calibration curves are steep because of quantizing.
>8 bit is OK for calibrated device and for traditional RGB abstract color
>spaces. But as soon as you apply the calibration on image the last become
>"uncalibrated" and in case of high degree of curvature you may got banding on
>gradients and loss of details.
>It's ok using PostScript at profiling stage because it's precise (the channel
>values passed from argyllcms in floating point format). But for real image
>printing you may need convert the sources into 16 bit before converting by
>cctiff. If your RIP doesn't support 16 bit or have a speed constraints with 16
>bit per channel CMYK images you may convert 16-bit "uncalibrated" image into 8
>bit with apllying some kind of dither.
>For example an ImageMagic command line:
>
>convert -verbose -ordered-dither o4x4,256 -depth 8 -compress LZW
>Input_from_Argyll.tif Output_to_RIP.tif
Hello Graeme!
As written abowe I ask a dither feature(s) for cctiff:
* dither by default when source TIFF image have 16 bit depth and destination
is JPEG;
* an option to force 8 bit output with 16 bit input. Default dithering for
that;
* an option to disable dither (for two cases abowe);
* an option to enable dithering with 16 bit source and destination both (may
be in precision mode only if useless in standard).
Nikolay Pokhilchenko.
Other related posts:
