GreyPEG is a macOS App that enables batch desaturating (greyscale) of JPEG files in a manner that does not alter the original files image integrity. Often when saving an edited image, generational artifacts can be introduced.
The application is a GUI (Graphical User Interface) to the JPEGTRAN command line tool. See our other app – SquarePusher if you have other lossless JPEG editing needs such as rotation, cropping, and mirroring.
Editor Operations:
- Desaturate – remove the color data from RGB / multi-channel image files.
Save Options:
- Drop / reset metadata – drops file data such as a image orientation, thumbnail, or EXIF metadata, that may be out of date for the edited version of image.
- Optimize file size – optimizes encoding parameters for a smaller (byte count) and more compact JPEG output file.
Editor Notes:
- Sandboxed macOS apps require user interaction to enable saving of files. Rather than being able to save JPGs in the original files location, we require a save / output location to be chosen during app launch. This location can be changed later on.
JPEGTRAN Notes:
- Input image size cannot be larger than 65,500 pixels per side [width/height]. The JPEG standard supports images up to 65,535 pixels per side, but JPEGTRAN does not natively support that upper limit.
- Some JPEG formats / color models are incompatible with the greyscale function.
Application Notes:
- Super high resolution images will load slowly. If you need to edit images like that SquarePusher may be a better option.
Privacy Notes:
- All editing / processing is done locally on the users macOS computer. No image data / snapshots are taken / transmitted.