RL Vision Knowledge Base
Support questions and answers for software by RL Vision.
Note: This is an archived discussion. Any bug, problem or suggestion mentioned here is likely to have been fixed since it was written.
Subject: Re: Question about PDF Image Extraction Wizard
Date: Sat, 22 Apr 2006 12:13:57 +0200The difference in result is probably due to the fact that bmp images are not
compressed. Images in pdfs are compressed, even if they are stored in a
lossless format. They can also be 8 (or less) bits, but the bmps are 24
bits.
PDF Wiz is actually only a frontend for another command line program. I
haven't created this program, so I can't tell you exactly what is happening
under the hood.
// Dan
----- Original Message -----
From: Troy
To: RL
Sent: Friday, April 21, 2006 8:57 PM
Subject: Re: Question about PDF Image Extraction Wizard
> > On Fri, Apr 21, 2006 at 08:33:49PM +0200, RL wrote:
>> > > PDF files can store images in both jpg and lossless format (usually both
>> > > depending on the type of image). It is up to the PDF creator software to
>> > > decide which format to use. PDF Wiz will extract all images in the
format
>> > > they are stored inside the file. It does not recompress any images.
> >
> > Hi Dan, and thanks for responding.
> >
> > As an example, the source PDF I am using is 24.9MB. PDF Image Extraction
> > Wizard produces a mixture of JPEGs and BMPs that total 324MB.
> >
> > If I zip the resulting images with maximum compression, the resulting file
> > is 81.9MB. Using RAR with best compression results in a 71.7MB archive.
> >
> > It seems like either something's not quite right with the output of your
> > software, or PDF has some kind of crazy magical compression algorithm for
> > images :-) , or something else is going on that I don't understand.
> >
> > The example PDF is a scan of an old magazine, one image per page in the
PDF.
> > You can download it for yourself here:
> >
> > http://www.deadwoodinc.net/amigan/acar/jan96.part1.rar
> > http://www.deadwoodinc.net/amigan/acar/jan96.part2.rar
> >
> > --
> > Troy
> > *****@*****
> > http://www.tdavis.org/
compressed. Images in pdfs are compressed, even if they are stored in a
lossless format. They can also be 8 (or less) bits, but the bmps are 24
bits.
PDF Wiz is actually only a frontend for another command line program. I
haven't created this program, so I can't tell you exactly what is happening
under the hood.
// Dan
----- Original Message -----
From: Troy
To: RL
Sent: Friday, April 21, 2006 8:57 PM
Subject: Re: Question about PDF Image Extraction Wizard
> > On Fri, Apr 21, 2006 at 08:33:49PM +0200, RL wrote:
>> > > PDF files can store images in both jpg and lossless format (usually both
>> > > depending on the type of image). It is up to the PDF creator software to
>> > > decide which format to use. PDF Wiz will extract all images in the
format
>> > > they are stored inside the file. It does not recompress any images.
> >
> > Hi Dan, and thanks for responding.
> >
> > As an example, the source PDF I am using is 24.9MB. PDF Image Extraction
> > Wizard produces a mixture of JPEGs and BMPs that total 324MB.
> >
> > If I zip the resulting images with maximum compression, the resulting file
> > is 81.9MB. Using RAR with best compression results in a 71.7MB archive.
> >
> > It seems like either something's not quite right with the output of your
> > software, or PDF has some kind of crazy magical compression algorithm for
> > images :-) , or something else is going on that I don't understand.
> >
> > The example PDF is a scan of an old magazine, one image per page in the
PDF.
> > You can download it for yourself here:
> >
> > http://www.deadwoodinc.net/amigan/acar/jan96.part1.rar
> > http://www.deadwoodinc.net/amigan/acar/jan96.part2.rar
> >
> > --
> > Troy
> > *****@*****
> > http://www.tdavis.org/