JohannI output each photo a full size 8-bit TIFF image, the run the following batch file on it, using ImageMagick, guetzli, jpegtran and exiftool:
- resize and sharpen, save as PNG image
- use guetzli to turn the PNG image into a JPEG image
- delete the PNG image
- turn the JPEG image into progressive JPEG, because why not
- copy the EXIF metadata from the original TIFF image to the compressed JPEG image
- rename the compressed JPEG image, delete the TIFF image and a leftover file created during the process
- resize and sharpen, save as PNG image
- use guetzli to turn the PNG image into a JPEG image
- delete the PNG image
- turn the JPEG image into progressive JPEG, because why not
- copy the EXIF metadata from the original TIFF image to the compressed JPEG image
- rename the compressed JPEG image, delete the TIFF image and a leftover file created during the process
convert.exe %1 -filter Lanczos -resize 1620x1620 -adaptive-sharpen 2.5x0.65+2.5+0.65 -format PNG %1.png
guetzli.exe --quality 90 %1.png %1_jpg
del %1.png
jpegtran.exe -optimize -copy all -progressive %1_jpg %1_jpg
exiftool.exe -wm cg -tagsfromfile %1 -all:all %1_jpg
ren *.tif_jpg *.jpg
del %1
del %1_jpg_original