BMP (Bitmap) is a standard file format for Windows. Which element specifies the dimensions, compression type, and color format for the bitmap?

BMP (Bitmap) is a standard file format for Windows. Which element specifies the dimensions, compression type, and color format for the bitmap?

• A. Header
• B. The RGBQUAD array
• C. Information header
• D. Image data

Answer: (B)

In BMP files, the information about the image’s size, how the data is stored, and how many colors are used comes from the bitmap information header. This header (the BITMAPINFOHEADER) contains fields for the width and height (dimensions), the bit count (color format), and the compression method. It’s exactly this piece of the structure that tells you how big the image is, what kind of color data you’re dealing with, and how the pixel data is laid out. The RGBQUAD array, by contrast, is the color palette used for indexed-color images. It maps palette indices to actual RGB values, but it doesn’t describe the image’s dimensions, compression, or color depth. The actual pixel data lives after the headers (and palette if present). So the element that specifies the dimensions, compression type, and color format is the information header.

In BMP files, the information about the image’s size, how the data is stored, and how many colors are used comes from the bitmap information header. This header (the BITMAPINFOHEADER) contains fields for the width and height (dimensions), the bit count (color format), and the compression method. It’s exactly this piece of the structure that tells you how big the image is, what kind of color data you’re dealing with, and how the pixel data is laid out.

The RGBQUAD array, by contrast, is the color palette used for indexed-color images. It maps palette indices to actual RGB values, but it doesn’t describe the image’s dimensions, compression, or color depth. The actual pixel data lives after the headers (and palette if present). So the element that specifies the dimensions, compression type, and color format is the information header.