JPEG stands for Joint Photographic Experts Group. It was established by the committee setup in 1986 by CCIT standards body. It was created in 1992 and approved in 1994. The jpg format is the most popular image format around the globe in the recent times.

JPEG is the format that compresses images. JPEG is an entirely lossy compression. The lossy compression means that when you decompress the image with this method, the quality is not alike the image was put in for compression.

The lossy image compression is one method to reduce the image size with the image quality. The lossy image compressor is different from the lossless jpeg compressor  because of lossy compression the image size is reduced too much and the quality of the compressed image is not identical to the original image.

 Lossy image  compression will modify the source stream that you lose information that can not be restored upon decompression. Basically the lossy image compressor reduces the number of similar scheme of colors in an image. Reducing the number of colors used in the image means shrinking the size of what image compressor do.

The lossy compression for JPEG files works in two methods for reducing the image size that covers extra storage. The methods include transform encoding and Chroma subsampling. These methods work after one another to produce a better quality image with condensed size.

Transform encoding

The transform encoding is the method of image compressor that works in a lossy image compressor for encoding values ​​in a JPEG file. Transform encoding uses mathematical function to portray data.

This method is an example of an image that uses DCT that creates the image in the background. This is then transformed to the second method of JPEG image compression; Chroma subsampling.

Chroma subsampling

The human visual eye is unable to detect the position of an image that can reduce the size of the image

The bandwidth can be optimized with the Chroma subsampling as the colors in ajpeg file can not be optimized with a naked eye. The Chroma stores the two similar luminance color in a single one that reduces the size of image.


These methods are built inside the image compressors that are entirely lossy. These work after one another to provide people with reduced size jpeg image.