REGION

REGION

The REGION structure defines the contents of an image partition. This structure is used to reference general-purpose image regions.

	Copy Code
typedef struct { BYTE Sig; BYTE Interlace; BYTE BitErr; REGION_FLAGS Flags; PIXEL_TYPE PixType; BYTE Bpp; WORD Width; WORD Height; SHORT Stride; DWORD Offset; } REGION;

Fields:

Name

Description

Sig

Must be 0.

Interlace

0 if not interlaced, 1 for PNG interface pattern, 2 for GIF interlace pattern. For PT_GRAY/PT_GRAYM JPEG 2000 images, bits 2-4 can hold the vertical subsampling factor minus one and bits 5-7 plus can hold the horizontal subsampling factor minus one.

Flags

Attributes of the region.

Value	Meaning
RF_TopDown	Set if image stored top line first, bottom last
RF_NonInter	(unused for now) Set if image is non-interleaved
RF_MakeGray	Set if region to be treated as gray scale
RF_SwapRB	Set to treat input component samples as interleaved in RGB order instead of interleaved in BGR order (Windows DIBs are in BGR order)
RF_2Byte	Set for <= 8 Bpp images if each sample occupies two bytes
RF_Signed	Set if sample values are to be interpreted as signed values
RF_BigEndian	Set when sample values occupy two bytes and the bytes are arranged in big-endian (Motorola) order instead of little-endian (Intel) order
RF_CM2RGB	Set if a color-mapped image is to be converted to a 3-component RGB image
RF_Channel	Set if a single color channel is to be used
RF_ChLo	If RF_Channel is set, ChHi is two bits whose value 0..3 indicate which color channel
RF_ChHi	If RF_Channel is set, ChLo is two bits whose value 0..3 indicate which color channel
RF_Packed	Not implemented

PixType

Type of pixels which comprise this region.

Value	Meaning
PT_NONE	Undefined or compressed pixels
PT_CM	Color mapped up to 256 colors
PT_GRAY	Gray scale up to 16 bits
PT_GRAYM	Gray scale up to 16 bits (big-endian)
PT_RGB	RGB 24, 48 bit (blue is low, red is high, Intel-ordered)
PT_RGBM	RGB 48 bit (blue is low, Motorola-ordered)
PT_RGB555	RGB 16 bit (xrrrrrgggggbbbbb - blue is low bits)
PT_RGB565	RGB 16 bit (rrrrrggggggbbbbb - blue is low bits)
PT_CMYK	CMYK 32 bit (cyan is low, black is high)
PT_GRAYA	Gray scale 1-16 bits with alpha, Intel-ordered
PT_GRAYAM	Gray scale 9-16 bits with alpha, Motorola-ordered
PT_RGBA	RGBA 32, 64 bit (blue is low, alpha is high, Intel-ordered)
PT_RGBAM	RGBA 64 bit (blue is low, alpha is high, Motorola-ordered)

Bpp

Meaningful bits per pixel

Width

Width of region in pixels > 0

Height

Height of region in pixels > 0

Stride

Width in bytes of area containing the region. This value is at least ( Width * Bpp + 7 ) / 8. The stride may be larger than these values if the region is contained within a larger region or if each line is padded (e.g., to a DWORD boundary for Windows bitmaps).

Offset

Offset in bytes of start of the region line whose offset has the smallest value. This is the offset of the top image line for a non-interlaced RF_TopDown image. It is the offset of the bottom image line for a non-interlaced image which is not RF_TopDown.