JPEGpakkauksen

JPEGpakkauksen refers to the process of compressing image data using the JPEG (Joint Photographic Experts Group) standard. JPEG is a widely used lossy compression method for digital images. Lossy compression means that some image data is discarded during the compression process to achieve smaller file sizes. This discarded data is usually imperceptible to the human eye, making it suitable for photographs and other complex images where perfect accuracy is not paramount.

The JPEG compression algorithm works by first converting the image from RGB color space to a luminance (Y) and chrominance (Cb, Cr) color space. The chrominance components, which carry color information, are then subsampled, meaning their resolution is reduced. This is because the human eye is less sensitive to color detail than to brightness. Following this, the image data is divided into 8x8 pixel blocks, and a Discrete Cosine Transform (DCT) is applied to each block. The DCT converts the spatial information in the block into frequency components.

Finally, quantization is applied. This step involves dividing the DCT coefficients by a quantization table, which effectively rounds off many of the coefficients, especially those representing higher frequencies (finer details). The degree of compression is controlled by the chosen quantization table and the quality setting selected by the user or software. Higher quality settings result in less aggressive quantization and larger file sizes, while lower quality settings lead to more aggressive quantization, smaller file sizes, and potentially more visible artifacts. Despite the data loss, JPEG is highly effective for typical photographic images, offering a good balance between image quality and file size.