use-revolution Digest, Vol 14, Issue 1

Frank Leahy frank at
Mon Nov 1 11:15:10 CST 2004

On Nov 1, 2004, at 5:00 PM, use-revolution-request at 

> From: "MisterX" <b.xavier at>
> Subject: RE: image size limit?
> To: "'How to use Revolution'" <use-revolution at>
> Message-ID: <20041101033545.21B1A93005C at>
> Content-Type: text/plain;	charset="us-ascii"
> How about reading half the image, and assembling after you resize and 
> take a
> snapshot?
> You can read half the image or by quarters Using a loop and reading 
> the file
> the "traditional" way with Open, read, close file...
> Just wondering... ;)

The JPEG format is a compressed format, with a header that may or may 
not contain EXIF information and a thumbnail, followed by the 
compressed data.  You cannot simply open the file, read half of it, and 
expect it to be half of the picture -- that's not how compression 
works.  You have to find the header, skip the header, and then 
uncompress it as you read each byte or sequence of bytes.

-- Frank

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