Currently, the dpi resolution of images extracted by pdfimages is lost. pdfimages should embed the original resolution in the extracted JPEGs. Additionally, TIFF should be an alternative to PBM/PPM since TIFFs can contain resolution information, too.
same for me.
pdfimages extracts all images with 72 dpi.
i have a example: the image in the pdf is 300 dpi and 302x103 pixel width/height. the extracted JPG image was 72 dpi with 1258x428 pixel width/height. so i can recalculate the origin resolution.
if you have all these informations, it must be easy to extract the image with origin resolution and pixel width/height.