Convert PJPEG to PPM

The PJPEG (Progressive JPEG) is a file extension for images that enhances the standard JPEG format by displaying images in successive waves of increasing detail, improving the user experience during slow network conditions. The JPEG stands for "Joint Photographic Experts Group", the organization that developed the standard in 1992. PJPEG is particularly useful for web applications, as it allows images to appear more quickly and progressively refine in quality, rather than loading from top to bottom like baseline JPEGs.

The Portable Pixmap (PPM) file extension, an image format within the Netpbm family, stores simple, uncompressed images. Introduced in the late 1980s, PPM supports RGB color and grayscale images, making it suitable for basic image processing and conversion tasks. Its plain text encoding simplifies debugging and data manipulation, although its lack of compression results in larger file sizes compared to modern formats. As such, PPM finds limited use in contemporary applications, mainly in educational and experimental settings where ease of implementation and readability are prioritized.