On 6/14/07, matthieu.villeneuve@free.fr matthieu.villeneuve@free.fr wrote:

Hello,

Selon Thibault Langlois tl@di.fc.ul.pt:

...

Hello,

I think there is a small bug in the grayscale version of the convolve method. Here is the diff:

$ diff convolve.lisp convolve-orig.lisp 64c64 < (incf sum (* (gray-intensity (image-pixel image x2 y2))

---

...

                          (incf sum (* (image-pixel image x2 y2)

That is correct, the faulty code probably remains from a version that didn't have alpha information in gray pixels. I'll fix that as soon as I can.

...

another detail: SBCL complaints about a declaration in color.lisp:

$ diff color.lisp color-orig.lisp 91,95c91 < (let ((colormap < #-sbcl(make-array 256 :element-type '(unsigned-byte 8)) < ;; make-color does not return an (unsigned-byte 8) sbcl does < ;; not like that.

< #+sbcl(make-array 256)))

...

(let ((colormap (make-array 256 :element-type '(unsigned-byte 8))))

Do you have any idea where exactly SBCL complains? It does not on my machine, but I may not use the library the same way you do...

I get a warning:

; caught WARNING: ; Asserted type (UNSIGNED-BYTE 8) conflicts with derived type ; (VALUES (INTEGER 4278190080 4294967295) &OPTIONAL). ; See also: ; The SBCL Manual, Node "Handling of Types"

This happens if I compile the MAKE-SIMPLE-GRAY-COLORMAP function.

I noticed another missing gray-intensity in convert.lisp:

wok:~/comp/lang/lisp/code/imago$ diff convert.lisp convert-orig.lisp 45c45 < (let ((gray (row-major-aref pixels i))) ---

  (let ((gray (gray-intensity (row-major-aref pixels i))))

Thanks for your time,

You are welcome, IMAGO is usefull so thank you !

-- Matthieu Villeneuve

Are you sure this version of the source code is up to date? I have

(let ((colormap (make-array 256 :element-type 'rgb-pixel)))

instead...

You are right I fetched the latest cvs and there is no problem.

I noticed two minor issues. - there is a 'g' char at the begining of convert.lisp

- regarding the convert methods, what should happen to the alpha channel ? Before loading the latest version I had modified some methods like this one:

(defmethod convert-to-grayscale ((image rgb-image)) (let* ((width (image-width image)) (height (image-height image)) (pixels (image-pixels image)) (result (make-instance 'grayscale-image :width width :height height)) (result-pixels (image-pixels result))) (dotimes (i (* width height)) (setf (row-major-aref result-pixels i) (make-gray (color-intensity (row-major-aref pixels i)) (color-alpha (row-major-aref pixels i))))) result))

what do you think ? should we have both kinds of convertion methods ?

Thibault