babl: improve alpha calc. in pal+alpha -> rgba conversion

... in particular, so that fully opaque pixels remain fully opaque

diff --git a/babl/babl-palette.c b/babl/babl-palette.c
index 8b8e529bbaf6dc3ff360805de399dcc0d38a5c23..823ff0c3421c6ae68d41404188786976f067b544 100644 (file)
--- a/babl/babl-palette.c
+++ b/babl/babl-palette.c
@@ -413,7 +413,7 @@ pala_u8_to_rgba_u8 (Babl          *conversion,
 
       palpx = pal->data_u8 + idx * 4;
       memcpy (dst, palpx, sizeof(char)*4);
-      dst[3] = (dst[3] * src[1]) >> 8;
+      dst[3] = (dst[3] * src[1] + 128) / 255;
 
       src += sizeof (char) * 2;
       dst += sizeof (char) * 4;