Re: Can read in the BMP data correctly ,but the size is not right?
Totally right!Thanks again! -- http://mail.python.org/mailman/listinfo/python-list
Re: Can read in the BMP data correctly ,but the size is not right?
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. -- http://mail.python.org/mailman/listinfo/python-list
Can read in the BMP data correctly ,but the size is not right?
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?
__Head_Info = [
[ 'Type' ,0 , 2],#BM
[ 'FSize',2 , 4],#File Size
[ 'Reserved' ,6 , 4],#0x
[ 'OffBits' ,10 , 4],#Offset of Image
[ 'SSize',14 , 4],# 40
[ 'Width',18 , 4],#Width
[ 'Height' ,22 , 4],#Hight
[ 'Planes' ,26 , 2],#1
[ 'BitCount' ,28 , 2],#{1,2,4,8,24}
[ 'Compress' ,30 , 4],#0
[ 'SizeImage',34 , 4],#Bytes Per Line
[ 'XPM' ,38 , 4],#2835
[ 'YPM' ,42 , 4],#2835
[ 'ClrUsed' ,46 , 4],#0
[ 'ClrImportant' ,50 , 4]#0
]
_Type =0;
_FSize =1;
_Reserved =2;
_OffBits =3;
_SSize =4;
_Width =5;
_Height=6;
_Planes=7;
_BitCount =8;
_Compress =9;
_SizeImage =10;
_XPM =11;
_YPM =12;
_ClrUsed =13;
_ClrImportant =14;
def __getInt( b, idx):
return binToInt(b,__Head_Info[idx][1],__Head_Info[idx][2])
def saveMatrixtoASC(bmpfilename,ascfilename):
try:
handle1=open( bmpfilename ,rb)
raw = bytearray(handle1.read( ))
handle1.close
except Exception as E:
return error:+ str(E),
datastart=__getInt(raw, _OffBits)
datasize =__getInt(raw, _SizeImage)
print ('Image Offset = 0x%X'%datastart)
print ('Image Size = 0x%X'%datasize)
handle2=open( ascfilename ,w)
for i in range(0,datasize):
handle2.write('0x%02X,'%raw[datastart+i])
if (i+1) % 16 == 0 :
handle2.write(\n)
handle2.close
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Re: Can read in the BMP data correctly ,but the size is not right?
On Tue, Apr 30, 2013 at 3:20 AM, Jimmie He jimmie...@gmail.com wrote: handle1.close I haven't looked at the rest of the code, but be careful of this: You aren't actually *calling* this function. That might be your problem and it might not, but try fixing it (add the parentheses, even though there's nothing to put in them) and see if that helps. Same with the handle2.close at the end. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Can read in the BMP data correctly ,but the size is not right?
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. -- http://mail.python.org/mailman/listinfo/python-list
Re: Can read in the BMP data correctly ,but the size is not right?
On 29/04/2013 18:20, 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? [snip] What size is 0x180? If you're asking why the file size is 0x180 and not 0x120, it's simply because of the header. An image file contains not just the pixels of the image, but also information about the image. -- http://mail.python.org/mailman/listinfo/python-list
Re: Can read in the BMP data correctly ,but the size is not right?
Jimmie He於 2013年4月30日星期二UTC+8上午1時20分49秒寫道：
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?
__Head_Info = [
[ 'Type' ,0 , 2],#BM
[ 'FSize',2 , 4],#File Size
[ 'Reserved' ,6 , 4],#0x
[ 'OffBits' ,10 , 4],#Offset of Image
[ 'SSize',14 , 4],# 40
[ 'Width',18 , 4],#Width
[ 'Height' ,22 , 4],#Hight
[ 'Planes' ,26 , 2],#1
[ 'BitCount' ,28 , 2],#{1,2,4,8,24}
[ 'Compress' ,30 , 4],#0
[ 'SizeImage',34 , 4],#Bytes Per Line
[ 'XPM' ,38 , 4],#2835
[ 'YPM' ,42 , 4],#2835
[ 'ClrUsed' ,46 , 4],#0
[ 'ClrImportant' ,50 , 4]#0
]
_Type =0;
_FSize =1;
_Reserved =2;
_OffBits =3;
_SSize =4;
_Width =5;
_Height=6;
_Planes=7;
_BitCount =8;
_Compress =9;
_SizeImage =10;
_XPM =11;
_YPM =12;
_ClrUsed =13;
_ClrImportant =14;
def __getInt( b, idx):
return binToInt(b,__Head_Info[idx][1],__Head_Info[idx][2])
def saveMatrixtoASC(bmpfilename,ascfilename):
try:
handle1=open( bmpfilename ,rb)
raw = bytearray(handle1.read( ))
handle1.close
except Exception as E:
return error:+ str(E),
datastart=__getInt(raw, _OffBits)
datasize =__getInt(raw, _SizeImage)
print ('Image Offset = 0x%X'%datastart)
print ('Image Size = 0x%X'%datasize)
handle2=open( ascfilename ,w)
for i in range(0,datasize):
handle2.write('0x%02X,'%raw[datastart+i])
if (i+1) % 16 == 0 :
handle2.write(\n)
handle2.close
The start of each line of bytes must be in the 32 bit=4byte
boundary in the MS BMP format.
Please read the MS specs.
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