PGM converter
JPG, PNG, WebP and GIF are turned into PGM, a black-and-white image with shades of gray. The format is simple and uncompressed. The pixel size does not change. Everything happens in the browser, files are not uploaded anywhere.
PGM, or Portable Graymap, is part of the Netpbm family and is intended for storing grayscale images. Like the related PBM and PPM formats, it was created for simple data exchange between programs and operating systems.
The file contains a short text header with the format identifier, the width, the height and the maximum brightness value. Then come the brightness values of each pixel. For the 8-bit variant the maximum value is 255, and compression is not applied.
Each pixel takes one byte, so the file is three times more compact than a full-color PPM, but still considerably larger than compressed formats. Transparency is not supported, and color information is irretrievably lost during conversion. For large files it is advisable to have enough RAM.
The format is in demand in machine vision, processing of medical and scientific images, and educational assignments on algorithms. The single-channel representation simplifies calculations: brightness can be analyzed without parsing color components. The result is available right after processing finishes.
The PGM converter turns a color image into shades of gray, taking into account that the eye perceives green as brighter than red and blue. Source JPG, PNG, WebP and GIF files are supported, and the size in pixels stays the same.
The conversion is performed on your device, and the source images are not sent to the network. Finished files are available for download one by one or all at once. After the page is closed, temporary data is removed from browser memory.