insert_bitmap and GIF/JPEG

[super...@gmail.com]

Hello guys.
I need to insert GIF/JPEG images to Excel worksheet. As XLWT can only
handle bitmaps (BMP) i convert the image to BMP with PIL:

img = Image.open('.seller')
img.convert('RGB')
img.save('.seller', 'BMP')

But unfortuantly that doesnt work:
Exception("bitmap isn't a 24bit true color bitmap.")

Can anyone help me out?

PS: According to PIL documentation (http://www.pythonware.com/library/
pil/handbook/concepts.htm) RGB = (3x8-bit pixels, true colour)

[John Machin]

On 13/03/2009 8:50 AM, super...@gmail.com wrote:
> Hello guys.
> I need to insert GIF/JPEG images to Excel worksheet. As XLWT can only
> handle bitmaps (BMP) i convert the image to BMP with PIL:
>
> img = Image.open('.seller')

Is '.seller' a GIF or a JPEG?
Why the somewhat unusual file-naming convention?

> img.convert('RGB')
> img.save('.seller', 'BMP')

Have you tried not saving it with the same name?

> But unfortuantly that doesnt work:
> Exception("bitmap isn't a 24bit true color bitmap.")
>
> Can anyone help me out?
>
> PS: According to PIL documentation (http://www.pythonware.com/library/
> pil/handbook/concepts.htm) RGB = (3x8-bit pixels, true colour)

It works for me (in my environment, on 1 sample JPEG file); details:

foo.jpg: copy of Water Lilies.jpg found in .../My Pictures/Samples/...
or some such folder

PIL: freshly installed from
http://effbot.org/downloads/PIL-1.1.6.win32-py2.6.exe

xlwt: 0.7.1

C:\xlwt\images>\python26\python
Python 2.6.1 (r261:67517, Dec 4 2008, 16:51:00) [MSC v.1500 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from PIL import Image
>>> img = Image.open('foo.jpg')
>>> img.convert('RGB')
<PIL.Image.Image instance at 0x00F6A058>
>>> img.save('bar', 'BMP')
>>> ^Z

'bar' is reported by various image programs as being a 24 bits-per-pixel
BMP file.

C:\xlwt\images>\python26\python
Python 2.6.1 (r261:67517, Dec 4 2008, 16:51:00) [MSC v.1500 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import xlwt
>>> wb = xlwt.Workbook()
>>> ws = wb.add_sheet("image")
>>> ws.insert_bitmap('bar', 2, 2)
>>> wb.save('bmp_from_jpg.xls')
>>> ^Z

Excel 2003 opens the file OK and the picture looks fine.

C:\xlwt\images>type dump_bmp_header.py
# dump BMP header
import struct, sys
fname = sys.argv[1]
data = open(fname, 'rb').read()
guff = struct.unpack("<2s6L2H", data[:30])
fmt = ("sig=%r, bitmap_size=%r, reserved1=%r, offset=%r,\n"
"header_len=%r, width=%r, height=%r, planes=%r, bit_count=%r")
print fmt % guff

C:\xlwt\images>dump_bmp_header.py python.bmp
sig='BM', bitmap_size=37446, reserved1=0, offset=54,
header_len=40, width=76, height=164, planes=1, bit_count=24

C:\xlwt\images>dump_bmp_header.py bar
sig='BM', bitmap_size=1440054, reserved1=0, offset=54,
header_len=40, width=800, height=600, planes=1, bit_count=24

Note that the code in Bitmap.py raises the exception that you saw if
bit_count != 24. It has already checked that sig == "BM". The next thing
that it will check is that planes == 1. Evidently planes are called
"frames" by some software. There's a possibility that your file may have
3 x 8 instead of 1 x 24.

Please tell us what your environment is.
Please run the dump_bmp_header.py on your file.
Can you send a copy of your original GIF/JPEG file?

Cheers,
John

[super...@gmail.com]

Thank you, for the response, John (:

Image i try to insert: http://i42.tinypic.com/oifzfp.jpg

My environment:
Debian Lenny
python 2.5.4
PIL 1.1.6
xlwt 0.7.1

Where can i find dump_bmp_header.py?

Sergei

[super...@gmail.com]

aww...sorry

here's the header:
sig='BM', bitmap_size=5878, reserved1=0, offset=1078,
header_len=40, width=160, height=30, planes=1, bit_count=8

Looks like it IS 8 bit

[super...@gmail.com]

Something happened with my prev. answers.

Image: http://i42.tinypic.com/oifzfp.jpg
Environment:
Debian Lenny
python 2.5.4
xlwt 0.7.1
PIL 1.1.6

[John Machin]

I don't know how you got 8 in there ....

C:\xlwt\images>\python26\python
Python 2.6.1 (r261:67517, Dec 4 2008, 16:51:00) [MSC v.1500 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from PIL import Image

>>> img = Image.open('oifzfp.jpg')
>>> img.convert('RGB')
<PIL.Image.Image instance at 0x00F8F2D8>
>>> img.save('oifzfp_conv.bmp', 'BMP')
>>> ^Z

C:\xlwt\images>dump_bmp_header.py oifzfp_conv.bmp
sig='BM', bitmap_size=14454, reserved1=0, offset=54,
header_len=40, width=160, height=30, planes=1, bit_count=24

*AND* I got the same effect when I left out the img.convert('RGB') step
... the JPEG file is already RGB.

So: I suggest that you either
(a) find another method of converting files to BMP format
or
(b) stick with PIL, gird up your loins, and do battle with the effbot :-)

Cheers,
John

[John Machin]

Already got that info (spread over two messages).

[super...@gmail.com]

Omg, i just realised that img.convert() doesnt change the object, u
need to use img = img.convert() instead.
Thank u John, everythin works perfect now.

Sergei

[John Machin]

Very strange. As I reported last time, omitting the convert step made no
difference.

C:\xlwt\images>\python26\python
Python 2.6.1 (r261:67517, Dec 4 2008, 16:51:00) [MSC v.1500 32 bit
(Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from PIL import Image

>>> img = Image.open('oifzfp.jpg')
>>> img.bits
8
>>> img.format
'JPEG'
>>> img.info
{'jfif_version': (1, 1), 'jfif': 257, 'jfif_unit': 2, 'jfif_density':
(0, 0)}
>>> img.mode
'RGB'
>>> img.save('.oifzfp_noconv_noext', 'BMP')
>>> ^Z

C:\xlwt\images>dump_bmp_header.py .oifzfp_noconv_noext

sig='BM', bitmap_size=14454, reserved1=0, offset=54,
header_len=40, width=160, height=30, planes=1, bit_count=24

==== see? no conversion step at all, got bit_count == 24

I can't get it to do bit_count = 8 at all. Did you post the wrong file
(oifzfp.jpg)?

In any case, any vague fears that xlwt was part of the problem seem to
have been well and truly dispelled.

Cheers,
John