Can read in the BMP data correctly ,but the size is not right?

[Jimmie He]

On Tuesday, April 30, 2013 1:57:07 AM UTC+8, Peter Otten wrote:
> Jimmie He wrote:
> 
> 
> 
> >    I'm trying to read in the BMP data by the the code below,and I'm check
> 
> >    the data array with WINHEX,and it is correct,but which confuse me is
> 
> >    why the size is 0x180,but the actual picture should be 48*48 = 0x120
> 
> >    bytes because I use 1-bit BMP not the 24bit BMP,could any one give some
> 
> >    hints?
> 
> 
> 
> According to wikipedia <http://en.wikipedia.org/wiki/BMP_file_format>
> 
> 
> 
> """
> 
> The size of each row is rounded up to a multiple of 4 bytes [...]
> 
> """
> 
> 
> 
> So 48/8 == 6 will be rounded to 8, and 8*48 == 384 == 0x180.
> 
> 
> 
> >         handle1=open( bmpfilename ,"rb")
> 
> >         raw = bytearray(handle1.read( ))
> 
> >         handle1.close
> 
> 
> 
> To actually do something the last line should be handle1.close(). I 
> 
> recommend
> 
> 
> 
> with open(bmpfilename ,"rb") as handle1:
> 
>     raw = bytearray(handle1.read())
> 
> 
> 
> instead which has the additional advantage that the file will be closed if 
> 
> an exception occurs in the with-suite.
I've successfully read the correct data from BMP now by your advice,thanks again Peter and other helpful guy.Especially the BMP_file_format from wiki,very Visualize.