Using GIMP as a Render Engine
As I started adding more images to my blog posts, I realized how much effort still went into optimizing them. Converting images into different formats, generating multiple resolutions, and tweaking settings takes up a lot of time. And to be honest, I’m not using the right tools neither.
That’s why I started looking for a way to automate at least part of this process. I explored various frontend solutions and packages that could integrate into my build process, but none of them offered the flexibility I needed and especially wanted.
Then I realized I’m already using GIMP for image editing, and it has plenty of export options. So I decided to investigate if I could automate the export process, and here’s the solution I came up with:
(define (batch-export-menu)
(let* ((image (car (gimp-image-list)))
(drawable (car (gimp-image-get-active-layer image)))
(filename (car (gimp-image-get-filename image))))
(batch-export image drawable filename)))
(define (batch-export image drawable filename)
(let* ((basename (substring filename 0 (- (string-length filename) 4))) )
;; Export JPEG
(file-jpeg-save RUN-NONINTERACTIVE image drawable
(string-append basename ".jpg") ;; Filename for output
(string-append basename ".jpg") ;; Raw filename
0.8 ;; Quality (0.0 - 1.0, lower means more compression, worse quality)
0 ;; Smoothing (0 - 1, higher smooths more, but can reduce artifacts)
TRUE ;; Optimize Huffman tables (can reduce file size slightly)
FALSE ;; Progressive JPEG (TRUE enables progressive loading)
"" ;; Comment
0 ;; Subsampling
0 ;; Baseline JPEG (0 = no, 1 = enforce baseline compatibility)
0 ;; Restart interval (0 = none)
0) ;; DCT method (0 = float, 1 = integer, 2 = fast integer)
;; Export PNG
(file-png-save2 RUN-NONINTERACTIVE image drawable
(string-append basename ".png") ;; Filename for output
(string-append basename ".png") ;; Raw filename
0 ;; Interlace (0 = none, 1 = Adam7 interlacing)
9 ;; Compression level (0 = fastest, 9 = smallest file size)
0 ;; BKGD chunk (0 = no, 1 = save background color)
0 ;; GAMMA chunk (0 = no, 1 = save gamma value)
0 ;; ICCP chunk (0 = no, 1 = embed ICC profile)
0 ;; OFFS chunk (0 = no, 1 = save image offset)
0 ;; PHYS chunk (0 = no, 1 = save resolution information)
0 ;; SRGB chunk (0 = no, 1 = save sRGB information)
TRUE) ;; Save EXIF/XMP metadata
;; Export WebP
(file-webp-save2 RUN-NONINTERACTIVE image drawable
(string-append basename ".webp") ;; Filename for output
(string-append basename ".webp") ;; Raw filename
0 ;; Preset (0 = default, 1 = picture, 2 = photo, 3 = drawing, 4 = icon, 5 = text)
0 ;; Lossless (0 = lossy, 1 = lossless)
80 ;; Quality (0 - 100, lower means more compression, worse quality)
0 ;; Alpha Quality (0 - 100, lower means more compression, worse quality)
0 ;; Animation (use layers for animation)
0 ;; Loop animation
0 ;; Minimize animation size
0 ;; Keyframe distance
0 ;; Save EXIF data
0 ;; Save IPTC data
0 ;; Save XMP data
0 ;; Not sure what this is for
0 ;; Not sure what this is for
0 ;; Not sure what this is for
0 ;; Not sure what this is for
0 ;; Default delay
0) ;; Force Delay
;; Export AVIF
(file-heif-av1-save RUN-NONINTERACTIVE image drawable
(string-append basename ".avif") ;; Filename for output
(string-append basename ".avif") ;; Raw filename
80 ;; Quality (0 - 100, lower means more compression, worse quality)
0) ;; Lossless (0 = lossy, 1 = lossless)
))
;; Register the script in GIMP
(script-fu-register
"batch-export-menu"
"Batch Export" ;; Menu label
"Exports the image in multiple formats"
"Max Bronner"
"Max Bronner"
"2021"
"" ;; All image types
SF-IMAGE "Image" 0
SF-DRAWABLE "Drawable" 0)
;; Add it to the File menu
(script-fu-menu-register "batch-export-menu" "<Image>/File/")You can easily modify the script to include additional export options or adjust settings to fit your needs. Most export options are explained in the comments within the script above.
To use the export script, simply place it in your GIMP scripts folder under C:\Users\AppData\Roaming\GIMP\2.10\scripts for Windows and ~\Library\Application Support\GIMP\2.10\scripts for macOS. Once it’s in place, open GIMP and find the batch export option under File > Batch Export.