gdal_translate COMPRESS=JPEG SyntaxError: invalid syntax error

Question

Following is the code I'm using to compress set of .tif images to .jpg. My objective is to iterate through each .tif image and create a new set of compressed jpg images.

from osgeo import gdal
import os
for filename in os.listdir(os.getcwd()):
    #print(filename.split("."))
    if(filename.split(".")[1] == "tif"):
        print(filename.split(".")[0])
        gdal_translate \
          -co COMPRESS=JPEG \
          -co TILED=YES \
          filename.split(".")[0].tif  filename.split(".")[0].jpg

Though I don't see an error in this code. I followed the technique mentioned in this blog post., I'm getting the following error when I try to execute the above code. The error message is:

  File "test.py", line 8
    -co COMPRESS=JPEG \
               ^
SyntaxError: invalid syntax
        

What seems to be the issue here?

Answer 1

It looks like you're attempting to save as JPEG files. In which case GDAL would use the JPEG raster driver. The JPEG raster driver does not have a COMPRESS= creation option. See the driver's documentation at https://gdal.org/drivers/raster/jpeg.html#raster-jpeg and scroll down to see the list of creation options.

In fact, setting a compression option to JPEG for a JPEG file wouldn't make sense, anyhow, as JPEGs are always JPEG compressed. It's just a matter of how much they are compressed (versus the quality retained - JPEG compression is lossy). You could use the QUALITY= creation option for JPEGs to control the quality versus compression.

Alternatively, you could save the files as TIFF files (using the GDAL GTIFF driver), and then you could use the COMPRESS=JPEG creation option which would use JPEG compression within a TIFF file. But the output files would be TIFFs, not JPEGs.

Answer 2

Apparently, this short shell script does what I want. The script is inspired from the answer that appeared in this post.

#!/bin/sh

for f in *.tif; do
     #gdal_translate -co COMPRESS=JPEG -co TILED=YES "$f" "${f%.*}.jpg"
     gdal_translate  "$f" "jpg/${f%.*}.jpg"
done