Unraveling the Secrets of JPEG Image Compression
The Power of JPEG
JPEG, or Joint Photographic Experts Group, is a household name in the world of digital images. As one of the most widely used compression techniques, it has revolutionized the way we store and share images. But have you ever wondered what makes JPEG files tick?
Decoding JPEG Headers
Most file formats, including JPEG, have headers that contain valuable information about the file. These headers are like hidden treasure chests, waiting to be unlocked. In the case of JPEG files, the headers contain details like image height, width, and color mode (grayscale or RGB). By tapping into these headers, we can extract the resolution of a JPEG image without relying on external libraries.
A Deep Dive into the Code
Let’s take a closer look at the source code that makes this possible. When opening the image in binary mode, we’re able to access the raw data that makes up the file. The height and width of the image are stored at specific positions (164th and 165th bytes, respectively) and are each 2 bytes long. However, it’s essential to note that this only applies to JPEG File Interchange Format (JFIF) standard images. If your image uses a different standard, like EXIF, the code won’t work.
Bitwise Magic
To convert the 2-byte values into usable numbers, we employ the bitwise shifting operator (<<). This clever trick allows us to extract the resolution of the image with precision. Finally, the resolution is displayed, giving us a glimpse into the inner workings of the JPEG file.
Related Reads
For more Python programming fun, be sure to check out our article on Python Program to Check the File Size.