[pdftex] jpeg compression?

George N. White III gnwiii at gmail.com
Sat Feb 10 13:52:40 CET 2007

On 2/9/07, Dave Z. <zhu_dave at yahoo.com> wrote:

> I've got lots of images to put in my report. I use graphicx
> package. But the
> file size gets too big. If I include 1 image, the file size is like
> 1MB. If I include more, it gets bigger. Is there anything that I could
> do about the file size?

How will the report be viewed: screen, inket print, typeset, etc.?
What is the total sixe of the image files?
Are the images all different or is the same image used multiple times?

It is usually best to convert the individual images to pdf.  There are
numerous free and commercial tools and pdf supports many ways to store
images, but Adobe Photoshop is the "gold standard".  Watch out for
free tools that convert indexed color images to RGB (3x larger).  The
individual PDF files should not be greatly larger than the original
images.  Pdftex is maintained by a relatively small group of people,
there are many more people developing tools to create pdf files, so it
makes no sense to limit yourself to what pdftex can do.

When size is a problem you need to consider tradeoffs in compression
levels (for jpeg), color depth (8, 24, or 32 bits per pixel are common
values), and resolution (for screen viewing you may want to downsample
to under 100 pixels per inch).  If you have images of different types
(e.g., line art where jpeg's lossy compression creates artifacts
combined with photographs where jpeg compression can greatly reduce
image size with only minor degradation in quality)
there are big benefits from using the appropriate representation for
each image type.   When pdf images are included using pdftex the
contents are just copied into the output file, so you will know if
size will be a problem before you run pdftex.

George N. White III <aa056 at chebucto.ns.ca>
Head of St. Margarets Bay, Nova Scotia

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