PIL: reading bytes from Image

[cyberco]

I'm using web.py to send an image to the client. This works
(shortened):

print open(path, "rb").read( )

but this doesn't:

img = Image.open(path )
img.thumbnail(( 10,10))
print img.getdata()

or

print img.load()


How do I get the bytes of the Image object? 'getdata()' seemed the
way, but unfortunately.. .

[Max Erickson]

Re: PIL: reading bytes from Image

"cyberco" <cyberco@gmail. comwrote:

I'm using web.py to send an image to the client. This works
(shortened):
>
print open(path, "rb").read( )
>
but this doesn't:
>
img = Image.open(path )
img.thumbnail(( 10,10))
print img.getdata()
>
or
>
print img.load()
>
>
How do I get the bytes of the Image object? 'getdata()' seemed the
way, but unfortunately.. .
>

getdata() returns the data in a PIL format. Saving the image, in a
format your client understands, to a file like object like
StringIO.String IO is an easy path to take.

Sparklines shows this in action:

http://bitworking.org/projects/sparklines/

max

[cyberco]

Re: PIL: reading bytes from Image

Thanks,

I've tried the StringIO option as follows:

=============== =============== ===
img = Image.open('/some/path/img.jpg')
img.thumbnail(( 640,480))
file = StringIO, StringIO()
img.save(file, 'JPEG')

=============== =============== ===

But it gives me:

=============== =============== ===

exceptions.Type Error Traceback (most
recent call last)

C:\Python24\lib \site-packages\PIL\Im age.py in save(self, fp, format,
**params)
1303
1304 try:
-1305 save_handler(se lf, fp, filename)
1306 finally:
1307 # do what we can to clean up

C:\Python24\lib \site-packages\PIL\Jp egImagePlugin.p y in _save(im, fp,
filename)
407 )
408
--409 ImageFile._save (im, fp, [("jpeg", (0,0)+im.size, 0,
rawmode)])
410
411 def _save_cjpeg(im, fp, filename):

C:\Python24\lib \site-packages\PIL\Im ageFile.py in _save(im, fp, tile)
464 bufsize = max(MAXBLOCK, im.size[0] * 4) # see RawEncode.c
465 try:
--466 fh = fp.fileno()
467 fp.flush()
468 except AttributeError:

TypeError: descriptor 'fileno' of 'file' object needs an argument
=============== =============== ===

It looks similar to the code in Sparklines except for the fact that
the latter creates an Image from scratch.

2B

Saving the image, in a
format your client understands, to a file like object like
StringIO.String IO is an easy path to take.
>
Sparklines shows this in action:
>

http://bitworking.org/projects/sparklines/

>
max

[Max Erickson]

Re: PIL: reading bytes from Image

"cyberco" <cyberco@gmail. comwrote:

Thanks,
>
I've tried the StringIO option as follows:
>
=============== =============== ===
img = Image.open('/some/path/img.jpg')
img.thumbnail(( 640,480))
file = StringIO, StringIO()

Is the above line exactly what you tried? If it is, the comma and
space in the line are likely the problem. Try either:

from StringIO import StringIO
file=StringIO()

or

import StringIO
file=StringIO.S tringIO()

(using file as a variable name can cause issues if you later want
access to the built in object 'file')

The following:

>>import Image
>>import StringIO
>>im=Image.new( 'RGB', (100,100))
>>fp=StringIO.S tringIO()
>>im.save(fp, 'jpeg')
>>len(fp.getval ue())

823

Works for me on python 2.5 on windows.


max

[Larry Bates]

Re: PIL: reading bytes from Image

cyberco wrote:

Thanks,
>
I've tried the StringIO option as follows:
>
=============== =============== ===
img = Image.open('/some/path/img.jpg')
img.thumbnail(( 640,480))
file = StringIO, StringIO()
img.save(file, 'JPEG')
>
=============== =============== ===
>
But it gives me:
>
=============== =============== ===
>
exceptions.Type Error Traceback (most
recent call last)
>
C:\Python24\lib \site-packages\PIL\Im age.py in save(self, fp, format,
**params)
1303
1304 try:
-1305 save_handler(se lf, fp, filename)
1306 finally:
1307 # do what we can to clean up
>
C:\Python24\lib \site-packages\PIL\Jp egImagePlugin.p y in _save(im, fp,
filename)
407 )
408
--409 ImageFile._save (im, fp, [("jpeg", (0,0)+im.size, 0,
rawmode)])
410
411 def _save_cjpeg(im, fp, filename):
>
C:\Python24\lib \site-packages\PIL\Im ageFile.py in _save(im, fp, tile)
464 bufsize = max(MAXBLOCK, im.size[0] * 4) # see RawEncode.c
465 try:
--466 fh = fp.fileno()
467 fp.flush()
468 except AttributeError:
>
TypeError: descriptor 'fileno' of 'file' object needs an argument
=============== =============== ===
>
It looks similar to the code in Sparklines except for the fact that
the latter creates an Image from scratch.
>
2B
>

>Saving the image, in a
>format your client understands, to a file like object like
>StringIO.Strin gIO is an easy path to take.
>>
>Sparklines shows this in action:
>>
>http://bitworking.org/projects/sparklines/
>>
>max

>
>

If it hasn't already bitten you it will: It is a BAD idea to use
'file' as a variable name. If you do, you mask the built-in file
function. That is why most people use fp or something else.

-Larry