The READ_BMP function reads a Microsoft Windows Version 3 device independent bitmap file (.BMP) and returns the image.
READ_BMP does not handle 1-bit-images or compressed images.
This routine is written in the IDL language. Its source code can be found in the file read_bmp.pro in the lib subdirectory of the IDL distribution.
Note: To find information about a potential BMP file before trying to read its data, use the QUERY_BMP function.
To open, read, and display a BMP file named foo.bmp in the current directory and store the color vectors in the variables R, G, and B, enter:
TV, READ_BMP('foo.bmp', R, G, B)
TVLCT, R, G, B
Many applications that use 24-bit BMP files outside IDL expect BMP files to be stored as BGR. For example, enter the following commands.
a = BYTARR(3, 200, 200, /NOZERO)
a[0, *, *] = 255
TV, a, /TRUE
WRITE_BMP, 'foo.bmp', a
If you open the .bmp file in certain bitmap editors, you may find that the square is blue.
image = READ_BMP('foo.bmp')
TV, image, /TRUE
image = READ_BMP('foo.bmp', /RGB)
TV, image, /TRUE
Result = READ_BMP( Filename, [, R, G, B] [, Ihdr] [, /RGB] )
Returns a byte array containing the image. Dimensions are taken from the BITMAPINFOHEADER of the file. In the case of 4-bit or 8-bit images, the dimensions of the resulting array are (biWidth, biHeight).
For 24-bit images, the dimensions are (3, biWidth, biHeight). Color interleaving is blue, green, red; i.e., Result[0,i,j] = blue, Result[1,i,j] = green, etc. The RGB keyword can be used to change the interleaving.
For 32-bit images, the dimensions are (4, biWidth, biHeight). Color interleaving is blue, green, red, alpha; i.e., Result[0,i,j] = blue, Result[1,i,j] = green, Result[2,i,j] = red, Result[3,i,j] = alpha. The RGB keyword can be used to change the interleaving.
A scalar string specifying the full path name of the bitmap file to read.
R, G, B
Named variables that will contain the color tables from the file. There 16 elements each for 4 bit images, 256 elements each for 8 bit images. Color tables are not defined or used for 24-bit or 32-bit images.
A named variable that will contain a structure holding the BITMAPINFOHEADER from the file.
Tag names in the a BITMAPINFOHEADER structure are as defined in the Microsoft Developer Network Library; see https://docs.microsoft.com/en-us/previous-versions//dd183376(v=vs.85) for details.
If this keyword is set, color interleaving of 16-, 24-, and 32-bit images will be R, G, B [, A] i.e., Result[0,i,j] = red, Result[1,i,j] = green, Result[2,i,j] = blue, and if there is an alpha channel, Result[3,i,j] = alpha.
Add support for 32-bit (RGBA) bitmaps files
IOPEN, WRITE_BMP, QUERY_BMP