如何在PNG或GIF文件中编写元数据？

Question

I use php GD library to create images and I need to attach a basic text string to each images. I know that the PNG and GIF format doesn’t support EXIF but I wonder if any trick could replace it. I am interested in any possible solution.

Answer 1

I think most softwares that can handle XMP writing can write XMP metadata to PNG files because XMP is the only metadata format that PNG supports. On top of my head the softwares I can think of are Picasa, XnView, and Daminion, all free (Daminion server version not free). For GIF I'm not sure, but I know it only 'partially' supports XMP.