I would really like to see these fixes included in a next PIL
release, if there will be one. (I also would like to see an egg
release, but that's a different story.)
Note, that I posted a similar fix (combining Florian's and your's) to
the list a long time ago (july 2006). There is a small difference
though, see below.
Maybe a test for these fixes should be added, but I can't see any
TIFF image tests at all in the PIL distribution.
Am 10.10.2007 um 16:18 schrieb Gary Bloom:
Here's a quick fix for the writing of the file, as well...
Before making the fix below, go to line 721 and change the '1' to a
'2' !
721: ifd[RESOLUTION_UNIT] = 1
becomes
721: ifd[RESOLUTION_UNIT] = 2
Then make the changes listed below. This is consistent with
those changes. This is a quick and dirty fix that I have not
tested extensively, but it quickly allows me to read and write TIFF
images with both the PIL and Photoshop, and each can see the DPI as
set by the other. It fixes the problem I've had with PIL reading/
writing TIFFs. Thanks, Florian!
Regards,
Gary Bloom
Sales Engineer
Sefas Innovation
www.sefas.com
============
[Image-SIG] BUG: PIL DPI trouble - fix for TIFF files (PIL 1.1.6)
Florian Höch lists+Image_SIG at hoech.org
Fri Oct 5 00:05:16 CEST 2007
Previous message: [Image-SIG] fromstring image question
Next message: [Image-SIG] Image transpose
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
PIL only adds a dpi entry in the info dictionary if no resolution unit
is specified in the TIFF file. This seems to be because of a
misinterpretation of resolution unit values: they have a different
meaning than in a JPEG file. JPEG: 0 = None; 1 = inches; 2 = cm.
TIFF: 1
= None; 2 = inches; 3 = cm (see
http://www.awaresystems.be/imaging/tiff/tifftags/
resolutionunit.html and
http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html)
Here's a quick fix:
Open TiffImagePlugin.py and go to line 577. Change the code:
xres = getscalar(X_RESOLUTION, (1, 1))
yres = getscalar(Y_RESOLUTION, (1, 1))
if xres and yres:
xres = xres[0] / (xres[1] or 1)
yres = yres[0] / (yres[1] or 1)
resunit = getscalar(RESOLUTION_UNIT, 1)
if resunit == 2: # Inches
self.info["dpi"] = xres, yres
elif resunit == 3: # Centimeters
self.info["dpi"] = xres * 2.54, yres * 2.54
When converting from inches to centimeters, shouldn't you rather
divide by 2.54 instead of multiplying?
else: # No absolute unit of measurement.
self.info["resolution"] = xres, yres
Regards,
Florian Hoech
_______________________________________________
Image-SIG maillist - Image-SIG@python.org
http://mail.python.org/mailman/listinfo/image-sig
Regards,
Markus Kemmerling
_______________________________________________
Image-SIG maillist - Image-SIG@python.org
http://mail.python.org/mailman/listinfo/image-sig
