GhostPDF - SMask with Matte needs the image colour space for the group

When we encounter an image with an SMask we must push an Isolated group
to render the image. If the SMask image has a /Matte entry, then we need
to push the group with the colour space of the image.

Since the image code is the only client for the transparency routine
pdfi_trans_begin_isolated_group() it's simples to make that routine take
an additional parameter which is the colour space to be used for the
group, or NULL if none.

We can then directly use the passed in colour space to set the params
ColorSpace member for the group.

To facilitate determining whether an image SMask has a Matte or not,
its convenient to modify pdfi_image_get_matte() to return a boolean
indicating that. This was in fact already being used for that purpose
(pdfi_image_setup_type3x) by checking the return value was positive,
but I think it's more obvious to have the function update a specific
boolean parameter.

This is propagated back through pdfi_do_image_smask() for the benefit
of pdfi_do_image().

This fixes 4 files:
tests_private/pdf/PDF_1.7_FTS/fts_26_2605.pdf
tests_private/pdf/uploads/bug700571.pdf

These 2 files only exhibited a problem with psddcmyk16 for some reason.
tests_private/pdf/sumatra/uninitialized_value_with_JPX_images.pdf
tests_private/pdf/PDF_1.7_FTS/fts_17_1718.pdf

1 files changed, 2 insertions, 2 deletions

diff --git a/pdf/pdf_trans.c b/pdf/pdf_trans.c
index 12047c325..93ab8a6c0 100644
--- a/pdf/pdf_trans.c
+++ b/pdf/pdf_trans.c
@@ -526,14 +526,14 @@ int pdfi_trans_end_simple_group(pdf_context *ctx)
 }
 
 
-int pdfi_trans_begin_isolated_group(pdf_context *ctx, bool image_with_SMask)
+int pdfi_trans_begin_isolated_group(pdf_context *ctx, bool image_with_SMask, gs_color_space *pcs)
 {
     gs_transparency_group_params_t params;
     gs_rect bbox;
 
     gs_trans_group_params_init(&params, 1.0);
 
-    params.ColorSpace = NULL;
+    params.ColorSpace = pcs;
     params.Isolated = true;
     params.Knockout = false;
     params.image_with_SMask = image_with_SMask;