Anarres

It’s been a slow start to the new year; but, here is a new package called trivial-freeimage. It wraps most of the FreeImage Library. I got this to work on Windows with CFFI 0.9.2 by building the FreeImage dll without stdcall linking. It was a simple edit to the header file. Anyway, here is a simple example that has functions to find the top and bottom of an image of text from a tiff-g4 scanned page:

(require 'asdf)
(require 'cffi)
(load "trivial-freeimage.lisp")
(in-package :trivial-freeimage)

(initialize 0)
;load a tiff-g4 image and get it's height and width
;width is divided by 8 due to 1 pixel per bit in tiff-g4 format

(defvar dib (load-image tiff "24.tif" 0))
(defvar height (get-height dib))
(defvar width (/ (get-width dib) 8))

;as soon as we find a black pixel notify
(defun row-has-black? (row)
	(loop for i from 0 upto (- width 1) do
		(if (> (mem-aref row :uchar i) 0)
			(return t))))

;find the top of the frame of text
(defun find-top (dib)
	(loop for row from (- height 1) downto 0 do
		(if (row-has-black? (get-scan-line dib row))
			(return (- height row)))))

;find the bottom of the frame
(defun find-bottom (dib)
	(loop for row from 0 upto height do
		(if (row-has-black? (get-scan-line dib row))
			(return (- height row)))))

;always unload your dib's or you will never free the memory
(unload-image dib)
(de-initialize)

Also, note that FreeImage stores DIB’s with the origin being in the bottom left.

One other example– to convert a tiff file to png:

(in-package :trivial-freeimage)
(initialize 0)
(defvar dib (load-image tiff "image.tif" 0))
(save-image png dib "image.png" 0)
(unload-image dib)
(unload-image dib2)
(de-initialize)

I will be posting more examples while I work on the documentation of how to use the wrapping. Also, I will continue to add more of FreeImage’s API to the wrapping. I plan on adding a higher package for image editing that will make use of trivial-freeimage.