[magick-users] plane group p4m (was: composite Dst_In transparency problem)

[Günter Bachelier]

Hello Anthony Thyssen.

> Add a  -matte  after reading in the images.

thank you;  this works. But now I get artifacts in a later
step (see below).

I have begun implementing the 4 seamless plane groups
(2 dimensional symmetry groups) applied on images with
IM. The goal is to built a more flexible (part) of the
Photoshop filter Terrazzo
(http://www.xaostools.com/products/terrmain.html).
I am working now on the second seamless plane group: p4m
and so far a tile is generated from an image with the following
IM commands:

1) convert -size $triangle_widthx$triangle_width -stroke red -fill red
-draw "polyline 1,1 $triangle_width,$triangle_width 1,triangle_width"
xc:none p4m_mask.png
2) convert image.jp2 -crop $triangle_widthx$triangle_width+$x1+$y1
image_p4m.png
3) composite p4m_mask.png image_p4m.png -matte -compose Dst_In
p4m_G1.png
4) convert p4m_G1.png -flop -rotate -90 p4m_G2.png
5) composite p4m_G1.png p4m_G2.png -compose Dst_Over p4m_tile_part.png
6) convert p4m_tile_part.png ( +clone -flop ) + append ( +clone -flip )
-append p4m_tile.png

(typical image sizes I am working with is 4000x4000
and triangle_width about 2000 to 3000)

In this configuration pixel artifacts are now shown on p4m_tile_part.png
(part 5))
at the line where p4m_G1.png  and p4m_G2.png are met each other
(diagonal top left - down right).
Before your "-matte" suggestion I tried a temporary solution with
"mogrify -transparent black p4m_G1.png" and this kind of pixel artifacts

was not shown.
Such pixel artifacts will become even more important to the next two
plane
groups p3m1 and p6m where more than two basic elements (G1 and G2)
were combined with "-compose Dst_Over".

Did someone have suggestions for such a pixel artifact problem?



Thank you
Günter Bachelier