软件包: jpegjudge (0.0.2-3)

determine which of two given jpegs (same size) is the original

Try to determine which same picture was saved at a higher quality, even if the picture was saved at low quality and later at a higher quality.

By a statistical analysis over the quantization table stored in a jpeg one could probably deduce the quality which the picture was saved (i.e. this particular save), but it in no way says anything about the picture quality itself (i.e. whether it has ever been saved at lower quality before since its creation). For example, one might have saved a jpeg picture at low quality, and later saved at a higher quality, yet the information lost during the first save can't be restored.