Re: NSBitMapRepresentation --> JPEG compression?
Re: NSBitMapRepresentation --> JPEG compression?
- Subject: Re: NSBitMapRepresentation --> JPEG compression?
- From: Marco S Hyman <email@hidden>
- Date: Mon, 29 Jun 2009 23:24:32 -0700
On Jun 29, 2009, at 4:12 PM, Chris Tracewell wrote:
The issue is that when using writeToFile my images have an extra 3
to 10 KB of size whether the image is really small or really big -
ie 5KB or 300KB. I am suspecting that my XCode generated images are
bigger for one of two reasons...
1) Adobe's JPEG compression is just plain better and unless I
develop my own JPEG compression algorithm I am hosed.
2) My Objective-C created images contain extra file meta data /
headers that are inflating the size a bit
Possible. Grab a copy of exiftool and run it against a both a
photoshop image and one saved using your method. It will tell
you what metadata is in each image.
I know that very old versions of photoshop would not save the
exif/iptc/whatever metadata which annoyed me no end as I find
the info quite worthwhile to have around. On the other hand,
my "prepare images for web page" script makes a point of stripping
everything out of thumbnail images.
If you can't figure out how to do it in your app take a look
at jhead. Your app could call "jhead -se -purejpg <filename>"
to do the job for you.
// marc
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