Re: how to detect if a jpeg file is progressive or not
H.S.(hs.samix@gmail.com) is reported to have said:
> Hi Wayne,
>
> I tried your way and converted all the image with quality 25. You are
> right, I couldn't notice any perceptual difference at normal size. The
> different is noticable only if you magnify the image.
>
> I had a total of 14 images of size 2272x1704 (taken by a 4 megapixel
> digital camera). I reduced them in size (682x511 pixels; or to 30%) and
> their quality (to 25). The reduced size images were taking a total of
> 2.7 MB at default quality. But by using quality 25, the disk space usage
> reduced to 0.608 MB! This is a great improvement. (I am still getting
> progressive jpegs as the output.)
Glad to hear it helped. I have added the '-interlace plane' to my
script, thanks to you, and am getting my images down a bit more as
well.
>
> Here is the command I used to do the conversion (it is a one long line):
> $> for f in *.jpg; do echo "$f"; bn=`basename "$f" .jpg`; convert
> -resize 30% -quality 25 -interlace plane "$f" ${bn}-small.jpg; done
Very nice. I used to do the convert to selected images in my Digikam
album's but had to go to a script since the last Digikam upgrade. It
seems the batch processing was left out in this version.
I'm glad you posted your query. I have learned something new again
this week! DU never fails!
Best Regards
Wayne
--
At the source of every error which is blamed on the computer you will
find at least two human errors, including the error of blaming it on
the computer.
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