Hi
Since the only baseline JPEG is mandatory (for JPEG-supporting printers) i
made a little schoolbook lossless baselinifier application.
However, there is also jpeg-{x,y}-dimension-supported
and jpeg-k-octets-supported to take into account.
Because of this, i'm looking in to the built-in downscaling in libjpeg (and
sane derivatives).
Even though it is limited to a max downscale factor of 8 it should cover
even quite extreme cases.
(This of course includes decompressing and recompressing the image and
isn't lossless).
However, with Exif headers adding orientation completely separately, the
question of which dimension is which arises.
>From what i understand Exif headers are mandatory to support. (And respect?)
I'll stick my neck out and say x=width=horizontal and y=height=vertical.
But with a Exif rotation of +/- 90 degrees, does the constraints apply to
before or after transformation?
I.e. to the data as stored in the JPEG steam or as imaged onto the page.
Most printers, sensibly, have the same limit in both dimensions, but i have
logs for at least one that doesn't (and of course it has the lowest values).
Is there an official definition, or should one be added?
(And should it maybe be recommended to not have these constraints differ?)
Br,
Anton
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