Add some image manipulation tricks

how_to

@@ -276,6 +276,15 @@ Video and audio editing:
 ImageMagick:
     crop to aspect ratio
         convert in.png -gravity center -crop 4:3 out.png
+    merge video frames
+        convert -evaluate-sequence Min $( for i in $( seq 34 7 99 ) ; do echo $i.png ; done ) every7th-frame.jpg
+        # Using frames 34 through 99 from a video, take every 7th frame and overlay it into a composite image.
+        # https://mastodon.social/@climagic/103166291952077813
+
+Decode webp:
+    # from google's libwebp
+    # jpeg isn't supported, use convert after that
+    dwebp in.webp -o out.png
 
 RE .net apps:
     ilspymono <list-of-deps.txt>(can be empty) <exe or dll to disassemble> <output dir>
@@ -591,11 +600,6 @@ Elegant deduplication lines in file:
     https://iridakos.com/how-to/2019/05/16/remove-duplicate-lines-preserving-order-linux.html
     awk '!visited[$0]++' your_file > deduplicated_file
 
-Decode webp:
-    # from google's libwebp
-    # jpeg isn't supported, use convert after that
-    dwebp in.webp -o out.png
-
 Run studiotax on wine:
     http://pnijjar.freeshell.org/2018/studiotax/
     WINEARCH=win32