Module Bmp

val check_header : string -> Images.header

Checks the file header

val load : string -> Images.load_option list -> Images.t

Loads a bmp image.

val save : string -> Images.save_option list -> Images.t -> unit

Save an image in bmp format file.

Below, they are all lower interfaces

The type of bmp images.

type bmp = {
bmpFileHeader : bitmapfileheader;(*

Bytes <0 14<

*)
bmpInfoHeader : bitmapinfoheader;(*

Bytes <14 54<

*)
bmpRgbQuad : Images.rgb array;(*

Bytes <54 ...

*)
bmpBytes : bytes;(*

Bytes <bfOffBits ...

*)
}

The Caml representation of a bmp bit map image. Fields are Caml values, the decoded versions of raw data in the file.

Structure of bitmaps files on disk :

  • BITMAPFILEHEADER : bytes 0 to 14 excluded
  • BITMAPINFOHEADER : bytes 14 to 54 excluded
  • RGBQUAD : color map
  • BYTES : bit map
and bitmapfileheader = {
bfType : int;(*

Bytes <0 2<

*)
bfSize : int;(*

Bytes <2 6<

*)
bfReserved1 : int;(*

Bytes <6 8<

*)
bfReserved2 : int;(*

Bytes <8 10<

*)
bfOffBits : int;(*

Bytes <10 14<

*)
}
and bitmapinfoheader = {
biSize : int;(*

Bytes <14 18<

*)
biWidth : int;(*

Bytes <18 22<

*)
biHeight : int;(*

Bytes <22 26<

*)
biPlanes : int;(*

Bytes <26 28<

*)
biBitCount : bibitcount;(*

Bytes <28 30<

*)
biCompression : bicompression;(*

Bytes <30 34<

*)
biSizeImage : int;(*

Bytes <34 38<

*)
biXPelsPerMeter : int;(*

Bytes <38 42<

*)
biYPelsPerMeter : int;(*

Bytes <42 46<

*)
biClrUsed : int;(*

Bytes <46 50<

*)
biClrImportant : int;(*

Bytes <50 54<

*)
}
and bicompression =
| BI_RGB(*

Specifies that the bitmap is not compressed.

*)
| BI_RLE8(*

Specifies a run-length encoded format for bitmaps with 8 bits per pixel. The compression format is a two-bytes format consisting of a count byte followed by a byte containing a color index.

*)
| BI_RLE4(*

Specifies a run-length encoded format for bitmaps with 4 bits per pixel. The compression format is a two-byte format consisting of a count byte followed by two word-length color indexes.

*)
and bibitcount =
| Monochrome(*

1 The bitmap is monochrome, and the bmiColors field must contain two entries. Each bit in the bitmap array represents a pixel. If the bit is clear, the pixel is displayed with the color of the first entry in the bmiColors table; if the bit is set, the pixel has the color of the second entry in the table.

*)
| Color16(*

4 The bitmap has a maximum of 16 colors, and the bmiColors field contains up to 16 entries. Each pixel in the bitmap is represented by a four-bit index into the color table. For example, if the first byte in the bitmap is 0x1F, then the byte represents two pixels. The first pixel contains the color in the second table entry, and the second pixel contains the color in the 16th table entry.

*)
| Color256(*

8 The bitmap has a maximum of 256 colors, and the bmiColors field contains up to 256 entries. In this case, each byte in the array represents a single pixel.

*)
| ColorRGB(*

24 The bitmap has a maximum of 2^24 colors. The bmiColors field is NULL, and each three bytes in the bitmap array represents the relative intensities of red, green, and blue, respectively, of a pixel.

*)
| ColorRGBA(*

32 The bitmap

*)
val load_bmp : string -> bmp
val save_bmp : string -> bmp -> unit

Load and save functions for BMP images.