Problem with thumbnails

Question

Hi,
I'm getting a rather worrying result when the wiki creates thumbnails for images and I wondered if other people are seeing it too.
If I upload a relatively large jpg to the site, ca. 270k, it creates a thumbnail (as it should)
However, the thumbnail is a .png (which in itself is not a problem)
However, the thumbnail is 750k in size! This is not what I expect from thumbnails!
Does anyone see the same or different?
I note that Apple have changed from using CoreGraphics to a custom, compiled, ObjectiveC plugin called appledrawstring which we have no option to tweak. I presume that appledrawstring is assuming some sort of graphic support that is only present in newer mac, I'm on an intel xServe so not a flaky machine.
Personally I have been reduced to hacking the imageUtilities.py file to stop it calling appledrawstring in the hope that Apple will overwrite it when they have sorted out the situation.
If lots of people see this effect I will log it as an error.

Answer 1

I have managed to solve the problem as far as I am concerned but I'm not sure it's a fix I can recommend to all of you
For a number of reasons associated with the desire to create a photo library theme for my sites I decided to install Python Image Libraries, see http://www.pythonware.com This is not a trivial task, the overall process takes about an hour and a half but it took me the best part of two days to do it right! If you're interested Google 'PIL Fink OS X' and take a look at the article by Colby Palmer, including the comments at the bottom. I can only say that it worked for me, eventually, on an xServe running 10.6.2 (If you try it and have problems drop a reply to this post and I'll try and help)
Anyway, once it's installed you have access to a rich suite of image manipulation utilities that you can include in the python code for teamsserver. Remember Apple may at any time in the future overwrite these hacks but my experience is that it's rare, they might solve your problem for you and it's easy to add the hacks back in if you keep backups of all the python....
Personally I replaced a section of the python in imageUtilities.py with the following....
def thumbnailedImagePathForImagePath(path, maxWidth = 500, maxHeight = 700):
"""This ... returns the thumbnail path"""
parentPath = os.path.dirname(path)
fileName = os.path.basename(path)
pieces = fileName.split('.')
name = '.'.join(pieces[:-1])
extension = pieces[-1].lower()
if extension in ('jpg', 'jpeg'):
logging.warn("image is a jpeg \n")
thumbName = name + '_thumb_.' + extension
thumbPath = os.path.join(parentPath, thumbName)
if os.path.exists(thumbPath):
return thumbPath
else:
(thumbWidth, thumbHeight) = appledrawstring.GetImageSize(path, 0)
if thumbWidth > maxWidth:
size = maxWidth, thumbHeight*maxWidth/thumbWidth
try:
im = Image.open(path)
im.thumbnail(size)
im.save(thumbPath, "JPEG")
except IOError:
loggin.warn( "cannot create thumbnail for", fileName)
return thumbPath
else:
return path
else:
thumbName = name + '_thumb_.png'
thumbPath = os.path.join(parentPath, thumbName)
if os.path.exists(thumbPath):
return thumbPath
else:
(thumbWidth, thumbHeight) = appledrawstring.GetImageSize(path, 0)
if thumbWidth > maxWidth or thumbHeight > maxHeight:
appledrawstring.ResizeImageToMaxWidthHeight(path, thumbPath, maxWidth, maxHeight, 0, 0)
return thumbPath
else:
return path
Note: you need to add the line
import Image
at the top of the document.
Double note: the formatter for this page has deleted all the indentation of the python code above, which is VITAL. But, if you can't work out what it should be you probably shouldn't be messing about in Python
To recap: The result is that if you upload a 273K jpg file that is larger than maxWidth you end up with a thumbnail jpg that is 73K in size rather than a png that is 738K in size. Which tends to reduce the time it takes to download the page.
p.s.
If you're interested,
I'm pretty convinced the problem is in Apples moving over to image libraries designed for graphics processing chips. (Which I agree is a good idea in principle) If you look at the HTML code that is generated for the thumbnails you will see they include information as to the size of the original image (as was the case in wiki 1) However, instead of giving the size of the original as 810*770 it's given as 809.89584738459584732*769.7463653283847463623, which rather suggests that the whole of the png is being stored as double precision floating point numbers, doh!