[gimp/gimp-2-10] plug-ins: in file-psd, fix u8 channel format

[Ell <ell src gnome org>]

commit ccc9bd1849b688536d00856f75ae2135af251ac6
Author: Ell <ell_se yahoo com>
Date:   Sun Apr 26 22:39:34 2020 +0300

    plug-ins: in file-psd, fix u8 channel format
    
    In file-psd, use a non-linear channel format when the image
    precision is u8 non-linear, as per gimp_image_get_channel_format().

 plug-ins/file-psd/psd-load.c |  3 ++-
 plug-ins/file-psd/psd-save.c | 24 +++++++++++++++++++-----
 2 files changed, 21 insertions(+), 6 deletions(-)
---
diff --git a/plug-ins/file-psd/psd-load.c b/plug-ins/file-psd/psd-load.c
index a73011efe8..972b3c367d 100644
--- a/plug-ins/file-psd/psd-load.c
+++ b/plug-ins/file-psd/psd-load.c
@@ -2538,7 +2538,8 @@ get_channel_format (PSDimage *img_a)
 
     case 8:
     case 1:
-      format = babl_format ("Y u8");
+      /* see gimp_image_get_channel_format() */
+      format = babl_format ("Y' u8");
       break;
 
     default:
diff --git a/plug-ins/file-psd/psd-save.c b/plug-ins/file-psd/psd-save.c
index 52eab07387..40475bb33b 100644
--- a/plug-ins/file-psd/psd-save.c
+++ b/plug-ins/file-psd/psd-save.c
@@ -1736,6 +1736,7 @@ get_bpc (gint32 image_id)
 static const Babl *
 get_pixel_format (gint32 drawableID)
 {
+  gint32       image_id = gimp_item_get_image (drawableID);
   const gchar *model;
   gint         bpc;
   gchar        format[32];
@@ -1766,7 +1767,7 @@ get_pixel_format (gint32 drawableID)
       g_return_val_if_reached (NULL);
     }
 
-  bpc = get_bpc (gimp_item_get_image (drawableID));
+  bpc = get_bpc (gimp_item_get_image (image_id));
 
   sprintf (format, "%s u%d", model, 8 * bpc);
 
@@ -1776,10 +1777,15 @@ get_pixel_format (gint32 drawableID)
 static const Babl *
 get_channel_format (gint32 drawableID)
 {
-  gint  bpc;
-  gchar format[32];
+  gint32 image_id = gimp_item_get_image (drawableID);
+  gint   bpc;
+  gchar  format[32];
 
-  bpc = get_bpc (gimp_item_get_image (drawableID));
+  /* see gimp_image_get_channel_format() */
+  if (gimp_image_get_precision (image_id) == GIMP_PRECISION_U8_GAMMA)
+    return babl_format ("Y' u8");
+
+  bpc = get_bpc (image_id);
 
   sprintf (format, "Y u%d", 8 * bpc);
 
@@ -1789,7 +1795,15 @@ get_channel_format (gint32 drawableID)
 static const Babl *
 get_mask_format (gint32 drawableID)
 {
-  return get_channel_format (drawableID);
+  gint32 image_id = gimp_item_get_image (drawableID);
+  gint   bpc;
+  gchar  format[32];
+
+  bpc = get_bpc (image_id);
+
+  sprintf (format, "Y u%d", 8 * bpc);
+
+  return babl_format (format);
 }
 
 static void