[gegl] newsprint: pass alpha channel through for black/white and RGB modes

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 46b8352a8b0bf8eb8a76b4898f1e4665a0b9c5ae
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Jul 14 02:44:43 2022 +0200

    newsprint: pass alpha channel through for black/white and RGB modes
    
    Fixing issue #307

 operations/common/newsprint.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/operations/common/newsprint.c b/operations/common/newsprint.c
index d641cafde..d827e5736 100644
--- a/operations/common/newsprint.c
+++ b/operations/common/newsprint.c
@@ -375,7 +375,7 @@ process (GeglOperation       *operation,
 
            for (int c = 0; c < 3; c++)
              out_pixel[c] = gray;
-           out_pixel[3] = 1.0;
+           out_pixel[3] = in_pixel[3];
 
            out_pixel += 4;
            in_pixel  += 4;
@@ -403,7 +403,7 @@ process (GeglOperation       *operation,
 
            for (int c = 0; c < 3; c++)
              out_pixel[c] = gray;
-           out_pixel[3] = 1.0;
+           out_pixel[3] = in_pixel[3];
 
            out_pixel += 4;
            in_pixel  += 4;
@@ -447,7 +447,7 @@ process (GeglOperation       *operation,
                                    o->angleboost,
                                    degrees_to_radians (o->angle4),
                                    o->aa_samples);
-           out_pixel[3] = 1.0;
+           out_pixel[3] = in_pixel[3];
 
            out_pixel += 4;
            in_pixel  += 4;