importing/exporting images with a transparent background

paolo mazza paolo.mazza at
Mon Dec 11 03:59:17 EST 2006

Thanks Jean-Paul . I think you are right. This has to be a bug.... and it
is quite annoying one. 

I tryed this:

I set the paintcompression to PNG 
I imported an image  (png)
I made a transparent hole with the eraser tool.
I moved to another card....and come back

- the image is opaque and the hole is white

- the image is opaque and the hole is black

If I  set the paintcompression to rle  it works fine ... and Rev keeps the

However, if I export this image to file as png  I get the same problem.
Thansparency has gone and the image is opaque with a white (MAC) of black
(WINDOWS) hole!

Any workaround for this?

Paolo Mazza

Le 9 déc. 06, à 19:00,  Paolo Mazza a écrit :

>> Dear Friends... I got a problem  importing images with a transparent
>> background... can you help me on this?
>> 1-I imported a picture (png file made by another program) into 
>> revolution
>> 2-I modifyed the image with the eraser tool and I got an area with a
>> trasparent backgroung (as expected)
>> 3- I exported this image as png
>> 4- I imported this emage again, and in MACOS the trasparent background 
>> is
>> white and the in WINDOWS the transparent backgound is black.
I have got  similar problems with PNG images and transparency.

You can try this short experiment, , check if you get  the same symptoms

1 (the paintcompression is set to PNG)
2 create any colored object
3  import a snapshot  (of anything except  the previous  colored object 
) and place it in front of the colored object
4 make a hole in the image, with the rubber for instance.  Through the 
hole, a part  of  the previous object can be seen,

(up to this point, no problem).

5 go to another card
6 come back to the card which contained the picture and its hole.
Here a problem may arise if the image is larger than approximately one 
square centimeter

On my mac computer , the image is completely opaque, the hole is 
closed,  the rubbed out part of the image is now white.

Strangely if the image is small enough, the transparency is still there 

this inconsistent  behavior leads me  to believe  it is caused by a bug.

If the compression is set to RLE, no problem.

This is why I  temporarily use only RLE compression, which is 
sufficient for my needs,  as long as I don't  use translucency  and 
don't have  to print  the images.


More information about the Use-livecode mailing list