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
else: # No absolute unit of measurement.
self.info["resolution"] = xres, yres
Regards,
Florian Hoech
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