[Image-SIG] Correctly determine image size of a Photoshop EPS

[kevin@cazabon.com]

EPS files don't have specific pixel dimensions - they're essentially a
vector format.  You may happen to have raster data embedded in it, but
that's besides the point.

The issue is likely the DPI or pixels/inch setting used to convert the image
to raster format.  Photoshop probably defaults to 300 pixels/inch or
something, while the others default to 72.

I'm not sure how you change the rendering res in PILfor EPS imports - but I
almost guarantee that's where you need to look.

Kevin.
----- Original Message ----- 
From: "Stefano Masini" <stefano at pragma2000.com>
To: <image-sig at python.org>
Sent: Monday, September 19, 2005 8:09 PM
Subject: [Image-SIG] Correctly determine image size of a Photoshop EPS


> Hello,
>
> I got hold of some EPS files evidently made with Photoshop.
> It seems I can't convert them to jpeg while retaining the correct
> size. The problem is that I need to know the original size because I
> have to make decisions depending on that.
>
> I've got one that when opened in Photoshop is 1315x890, but anything
> else gives me a 316x214 image. I tried with pil, imagemagick, exiftool
> and freeimage. I think all of them except exiftool rely on
> ghostscript.
>
> I figured the problem must be the BoundingBox being set to 0 0 316 214.
>
> This is extracted from the eps file:
>
> %%Creator: Adobe Photoshop Version 7.0
> %%Title: 102251N_c.eps
> %%CreationDate: Fri Sep 16 2005 18:31:35
> %%BoundingBox: 0 0 316 214
> %%HiResBoundingBox: 0 0 315.6 213.6
> %%SuppressDotGainCompensation
> %%DocumentProcessColors: Cyan Magenta Yellow Black
> %%EndComments
> %%BeginProlog
> %%EndProlog
> %%BeginSetup
> %%EndSetup
> %ImageData: 1315 890 8 4 0 1 6 "beginimage"
> %BeginPhotoshop: 6362
>
> So, first question: why is the BoundingBox set this way? Is it plain
> wrong, or is there a rationale behind?
>
> Then I see the non standard %ImageData field. I found the following
> info bout it:
>
> Photoshop 6.0 SDK
> EPS Parameters for ImageData (Photoshop 3.0 and later)
>
> columns      Width of the image in pixels
> rows         Height of the image in pixels
> depth        Number of bits per channel. Must be 1 or 8
> mode         Image mode. Bitmap/grayscale = 1; Lab = 2; RGB = 3; CMYK = 4
> pad channels Number of other channels stored in the file.
>              Ignored when reading...
> block size   Number of bytes per row per channel.
>              Will be either 1 or formula (below):
>              1 = Data is interleaved
>              (columns*depth+7)/8 = Data is stored in line interleaved
format
>              or there is only one channel
> binary/ascii 1 = Data is in binary format
>              2 = Data is in hex ascii format
> data start   Entire PostScriptline immediately preceding the image data.
>              This entire line should not occur elewhere in the PostScript
>              header code, but it may occur at part of line
>
> So, since this is documented, why is it not implemented in any tool?
> I guess I can answer that: because it's not standard and could change
> without notice.
>
> But then I wonder: isn't there any support at all? How can a poor soul
> know the size of a photoshop eps file without opening it with
> photoshop?
>
> I can't believe others didn't have this problem. Did everybody have to
> implement their own dirty parser and search for the %ImageData field
> by themselves?
>
> Please help a poor soul,
> thanks!
> stefano
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