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BITMAPV4HEADER structure

The BITMAPV4HEADER structure is the bitmap information header file. It is an extended version of the BITMAPINFOHEADER structure.

Applications can use the BITMAPV5HEADER structure for added functionality.

Syntax


typedef struct {
  DWORD        bV4Size;
  LONG         bV4Width;
  LONG         bV4Height;
  WORD         bV4Planes;
  WORD         bV4BitCount;
  DWORD        bV4V4Compression;
  DWORD        bV4SizeImage;
  LONG         bV4XPelsPerMeter;
  LONG         bV4YPelsPerMeter;
  DWORD        bV4ClrUsed;
  DWORD        bV4ClrImportant;
  DWORD        bV4RedMask;
  DWORD        bV4GreenMask;
  DWORD        bV4BlueMask;
  DWORD        bV4AlphaMask;
  DWORD        bV4CSType;
  CIEXYZTRIPLE bV4Endpoints;
  DWORD        bV4GammaRed;
  DWORD        bV4GammaGreen;
  DWORD        bV4GammaBlue;
} BITMAPV4HEADER, *PBITMAPV4HEADER;

Members

bV4Size

The number of bytes required by the structure. Applications should use this member to determine which bitmap information header structure is being used.

bV4Width

The width of the bitmap, in pixels.

If bV4Compression is BI_JPEG or BI_PNG, bV4Width specifies the width of the JPEG or PNG image in pixels.

bV4Height

The height of the bitmap, in pixels. If bV4Height is positive, the bitmap is a bottom-up DIB and its origin is the lower-left corner. If bV4Height is negative, the bitmap is a top-down DIB and its origin is the upper-left corner.

If bV4Height is negative, indicating a top-down DIB, bV4Compression must be either BI_RGB or BI_BITFIELDS. Top-down DIBs cannot be compressed.

If bV4Compression is BI_JPEG or BI_PNG, bV4Height specifies the height of the JPEG or PNG image in pixels.

bV4Planes

The number of planes for the target device. This value must be set to 1.

bV4BitCount

The number of bits-per-pixel. The bV4BitCount member of the BITMAPV4HEADER structure determines the number of bits that define each pixel and the maximum number of colors in the bitmap. This member must be one of the following values.

ValueMeaning
0 The number of bits-per-pixel is specified or is implied by the JPEG or PNG file format.
1The bitmap is monochrome, and the bmiColors member of BITMAPINFO contains 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.
4The bitmap has a maximum of 16 colors, and the bmiColors member of BITMAPINFO contains up to 16 entries. Each pixel in the bitmap is represented by a 4-bit index into the color table. For example, if the first byte in the bitmap is 0x1F, 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 sixteenth table entry.
8The bitmap has a maximum of 256 colors, and the bmiColors member of BITMAPINFO contains up to 256 entries. In this case, each byte in the array represents a single pixel.
16The bitmap has a maximum of 2^16 colors. If the bV4Compression member of the BITMAPV4HEADER structure is BI_RGB, the bmiColors member of BITMAPINFO is NULL. Each WORD in the bitmap array represents a single pixel. The relative intensities of red, green, and blue are represented with five bits for each color component. The value for blue is in the least significant five bits, followed by five bits each for green and red, respectively. The most significant bit is not used. The bmiColors color table is used for optimizing colors used on palette-based devices, and must contain the number of entries specified by the bV4ClrUsed member of the BITMAPV4HEADER.

If the bV4Compression member of the BITMAPV4HEADER is BI_BITFIELDS, the bmiColors member contains three DWORD color masks that specify the red, green, and blue components of each pixel. Each WORD in the bitmap array represents a single pixel.

24The bitmap has a maximum of 2^24 colors, and the bmiColors member of BITMAPINFO is NULL. Each 3-byte triplet in the bitmap array represents the relative intensities of blue, green, and red for a pixel. The bmiColors color table is used for optimizing colors used on palette-based devices, and must contain the number of entries specified by the bV4ClrUsed member of the BITMAPV4HEADER.
32The bitmap has a maximum of 2^32 colors. If the bV4Compression member of the BITMAPV4HEADER is BI_RGB, the bmiColors member of BITMAPINFO is NULL. Each DWORD in the bitmap array represents the relative intensities of blue, green, and red for a pixel. The value for blue is in the least significant 8 bits, followed by 8 bits each for green and red. The high byte in each DWORD is not used. The bmiColors color table is used for optimizing colors used on palette-based devices, and must contain the number of entries specified by the bV4ClrUsed member of the BITMAPV4HEADER.

If the bV4Compression member of the BITMAPV4HEADER is BI_BITFIELDS, the bmiColors member contains three DWORD color masks that specify the red, green, and blue components of each pixel. Each DWORD in the bitmap array represents a single pixel.

 

bV4V4Compression

The type of compression for a compressed bottom-up bitmap (top-down DIBs cannot be compressed). This member can be one of the following values.

ValueDescription
BI_RGBAn uncompressed format.
BI_RLE8A run-length encoded (RLE) format for bitmaps with 8 bpp. The compression format is a 2-byte format consisting of a count byte followed by a byte containing a color index. For more information, see Bitmap Compression.
BI_RLE4An RLE format for bitmaps with 4 bpp. The compression format is a 2-byte format consisting of a count byte followed by two word-length color indexes. For more information, see Bitmap Compression.
BI_BITFIELDSSpecifies that the bitmap is not compressed. The members bV4RedMask, bV4GreenMask, and bV4BlueMask specify the red, green, and blue components for each pixel. This is valid when used with 16- and 32-bpp bitmaps.
BI_JPEG Specifies that the image is compressed using the JPEG file interchange format. JPEG compression trades off compression against loss; it can achieve a compression ratio of 20:1 with little noticeable loss.
BI_PNG Specifies that the image is compressed using the PNG file interchange format.

 

bV4SizeImage

The size, in bytes, of the image. This may be set to zero for BI_RGB bitmaps.

If bV4Compression is BI_JPEG or BI_PNG, bV4SizeImage is the size of the JPEG or PNG image buffer.

bV4XPelsPerMeter

The horizontal resolution, in pixels-per-meter, of the target device for the bitmap. An application can use this value to select a bitmap from a resource group that best matches the characteristics of the current device.

bV4YPelsPerMeter

The vertical resolution, in pixels-per-meter, of the target device for the bitmap.

bV4ClrUsed

The number of color indexes in the color table that are actually used by the bitmap. If this value is zero, the bitmap uses the maximum number of colors corresponding to the value of the bV4BitCount member for the compression mode specified by bV4Compression.

If bV4ClrUsed is nonzero and the bV4BitCount member is less than 16, the bV4ClrUsed member specifies the actual number of colors the graphics engine or device driver accesses. If bV4BitCount is 16 or greater, the bV4ClrUsed member specifies the size of the color table used to optimize performance of the system color palettes. If bV4BitCount equals 16 or 32, the optimal color palette starts immediately following the BITMAPV4HEADER.

bV4ClrImportant

The number of color indexes that are required for displaying the bitmap. If this value is zero, all colors are important.

bV4RedMask

Color mask that specifies the red component of each pixel, valid only if bV4Compression is set to BI_BITFIELDS.

bV4GreenMask

Color mask that specifies the green component of each pixel, valid only if bV4Compression is set to BI_BITFIELDS.

bV4BlueMask

Color mask that specifies the blue component of each pixel, valid only if bV4Compression is set to BI_BITFIELDS.

bV4AlphaMask

Color mask that specifies the alpha component of each pixel.

bV4CSType

The color space of the DIB. The following table lists the value for bV4CSType.

ValueMeaning
LCS_CALIBRATED_RGBThis value indicates that endpoints and gamma values are given in the appropriate fields.

 

See the LOGCOLORSPACE structure for information that defines a logical color space.

bV4Endpoints

A CIEXYZTRIPLE structure that specifies the x, y, and z coordinates of the three colors that correspond to the red, green, and blue endpoints for the logical color space associated with the bitmap. This member is ignored unless the bV4CSType member specifies LCS_CALIBRATED_RGB.

Note  A color space is a model for representing color numerically in terms of three or more coordinates. For example, the RGB color space represents colors in terms of the red, green, and blue coordinates.

bV4GammaRed

Tone response curve for red. This member is ignored unless color values are calibrated RGB values and bV4CSType is set to LCS_CALIBRATED_RGB. Specify in unsigned fixed 16.16 format. The upper 16 bits are the unsigned integer value. The lower 16 bits are the fractional part.

bV4GammaGreen

Tone response curve for green. Used if bV4CSType is set to LCS_CALIBRATED_RGB. Specify in unsigned fixed 16.16 format. The upper 16 bits are the unsigned integer value. The lower 16 bits are the fractional part.

bV4GammaBlue

Tone response curve for blue. Used if bV4CSType is set to LCS_CALIBRATED_RGB. Specify in unsigned fixed 16.16 format. The upper 16 bits are the unsigned integer value. The lower 16 bits are the fractional part.

Remarks

The BITMAPV4HEADER structure is extended to allow a JPEG or PNG image to be passed as the source image to StretchDIBits.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Wingdi.h (include Windows.h)

See also

Bitmaps Overview
Bitmap Structures
BITMAPINFO
BITMAPINFOHEADER
BITMAPV5HEADER
CIEXYZTRIPLE
CreateDIBitmap
LOGCOLORSPACE
StretchDIBits

 

 

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