With a top-down DIB, the first byte in memory is the top-left pixel of the image.ĭirectDraw uses top-down DIBs. The bottom row of the image is the last row in the buffer. The top row of the image is the first row in memory, followed by the next row down. In a top-down DIB, the order of the rows is reversed. The following diagram shows the physical layout of a bottom-up DIB. Therefore, the first byte in memory is the bottom-left pixel of the image. The top row of the image is the last row in the buffer. In a bottom-up DIB, the image buffer starts with the bottom row of pixels, followed by the next row up, and so forth. In two different orientations, bottom-up and top-down. In Windows, device-independent bitmaps (DIBs) can be placed in memory However, this is not necessarily the case. So that the top row of the image appeared at the start of the buffer, followed by the next row, and so forth. If you are new to graphics programming, you might expect that a bitmap would be arranged in memory Memory : Top-Down DIB : origin is the upper- left corner. Memory : Bottom-Up DIB : origin is the lower- left corner This is valid when used with 16- and 32-bpp bitmaps. That specify the red, green, and blue components, respectively, of each pixel. Specifies that the bitmap is not compressed and that the color table consists of three DWORD color masks If biCompression is BI_JPEG or BI_PNG, the biHeight member specifies the height of the decompressed JPEG or PNG image file, respectively. If biHeight is negative, indicating a top-down DIB, biCompression must be either BI_RGB or BI_BITFIELDS. If biHeight is negative, the bitmap is a top-down DIB and its origin is the upper-left corner. If biHeight is positive, the bitmap is a bottom-up DIB and its origin is the lower-left corner. If biCompression is BI_JPEG or BI_PNG, the biWidth member specifies the width of the decompressed JPEG or PNG image file, respectively.

Delphi bitmap grayscale