Understanding bmp image files

[pranav]

Hello,
I want to read a BMP file, do some processing and then write it in a
new file. The problem is in the third step. For reading the file, i
have converted the file into decimal numbers, representing the pixel
values. Then i perform calculations on those decimal numbers. Now i am
unable to convert those into the format as required by the "bmp" file.
Any one, who is into image reading/manipulation, please help.

 

[Marc 'BlackJack' Rintsch]

I want to read a BMP file, do some processing and then write it in a
new file. The problem is in the third step. For reading the file, i
have converted the file into decimal numbers, representing the pixel
values.

You have converted the data into numbers, not "decimal" numbers.

Then i perform calculations on those decimal numbers. Now i am
unable to convert those into the format as required by the "bmp" file.
Any one, who is into image reading/manipulation, please help.

How have you converted the bytes into numbers and why can't you reverse
that step?

Ciao,
Marc 'BlackJack' Rintsch

 

[Paul McGuire]

Hello,
I want to read a BMP file, do some processing and then write it in a
new file. The problem is in the third step. For reading the file, i
have converted the file into decimal numbers, representing the pixel
values. Then i perform calculations on those decimal numbers. Now i am
unable to convert those into the format as required by the "bmp" file.
Any one, who is into image reading/manipulation, please help.

Here is a link to a *very* crude BMP file utility I wrote a long time
ago. (http://www.geocities.com/ptmcg/python/index.html#bmp) Follow
the highlighted "module" link to see the underlying code - there are
methods for saving the BMP data to a file. Perhaps those samples
might give you some insight on what is required.

(I would probably rewrite this to use the struct module nowadays, but
this code works as is.)

-- Paul

 

[Terry Reedy]

| Hello,
| I want to read a BMP file, do some processing and then write it in a
| new file. The problem is in the third step. For reading the file, i
| have converted the file into decimal numbers, representing the pixel
| values. Then i perform calculations on those decimal numbers. Now i am
| unable to convert those into the format as required by the "bmp" file.
| Any one, who is into image reading/manipulation, please help.

I would look into PIL, PyGame, and Numeric/Numpy.

 

[Paul McGuire]

| Hello,
| I want to read a BMP file, do some processing and then write it in a
| new file. The problem is in the third step. For reading the file, i
| have converted the file into decimal numbers, representing the pixel
| values. Then i perform calculations on those decimal numbers. Now i am
| unable to convert those into the format as required by the "bmp" file.
| Any one, who is into image reading/manipulation, please help.

I would look into PIL, PyGame, and Numeric/Numpy.

My mistake, for some reason I thought the OP wanted to read a BMP file
directly, and the code I cited shows the guts of writing out a BMP
file so he might get an idea about the file's structure - to address
the OP's actual question, I would second the recommendation to use PIL
to read, manipulate, and write back out the pixel values.

-- Paul