Some clarification to Tom's reflection of my comments with regard to TIFF-FX
support for drawing surfaces.
First let me reiterate that Profile M of TIFF-FX does have provisions for
drawing surface definition.
The Profile M format was developed to store compound images based on the
multi-layer Mixed Raster Content (MRC) imaging model, defined in ITU-T T.44.
A compound image is an image that may contained scanned images, synthetic
images or both. A Profile M page may contain one or more image types, such
as: multi-level continuous-tone or palletized color usually associated with
naturally occurring images; bi-level detail associated with the text and
line-art. These image types are processed in multiple separate layers. A
page consists of a background (BG) layer (i.e. drawing surface) and one or
more mask (M) and foreground (FG) layout image object pairs, which when
imaged in the specified sequence, starting with the background, will give
the desired page image. Mask layers are binary and has only one component
while the background and foreground layers can be gray or color and needs
one or more components. To apply the layout image objects to the page when
building up the desired page image, the FG is applied to the page through
its mask layer 'M' associated with it in the layout image object pair. That
is, what is added to the drawing surface is the product of the mask and
foreground layers. The following equation shows the model for combining
drawing surface (BG) and a sequence of layout image object pairs from left
Page Image = BG + M0xFG0 + M1xFG1 + M2xFG2 + ...
To minimize archiving and transmission file size, the page (i.e. drawing
surface) resolution and dimensions are specified in the first mask layer
(i.e. M0), which is referenced as the Primary Mask or Primary IFD (i.e. the
main IFD when considering the TIFF structure, it is the IFD that sits in the
main IFD chain of a series of linked pages). This allows the typically
multi-component background layer to be represented at a much lower
resolution, for significant savings. During the recombination process the
resolution of the BG, as well as all the other layers, is scaled to that of
the Primary Mask.
There is no real issue for Profile M to be used in accommodating variable
Ignore my comment with regard to a device that doesn't understand the
multi-layer Profile M structure attempting to display a multi-layered
Profile M file and the resulting image being less than what was intended. It
should be ignore because common practice is for a renderer to not attempt to
display or print a format that it does not understand. In the event of such
an occurrence, the resulting image would be only that contained in the
Primary IFD (Primary Mask), since the Primary IFD is the only IFD that would
be visible to such a render. If a Profile M Primary IFD contains the
character shapes of the text portion of a page, which is typical, the
down-level render would be able to display/print only the text content. It
would not have access to the BG or the FG information therefore the
background (drawing surface) color on which the text is rendered may be
incorrect if it were specified by BG to be other than white. Likewise any
color images or text color represented in the FG would be lost. As you
should now understand, this does NOT create any unusual issue for Profile M
to be used in accommodating variable drawing surfaces.
> -----Original Message-----
> From: Hastings, Tom N
> Sent: Friday, April 20, 2001 3:58 PM
> To: IPP FAX DL (E-mail)
> Cc: Lloyd McIntyre (E-mail)
> Subject: UIF - TIFF/FX does have a way to do variable drawing
> The current UIF document has the following issue:
> 1. It is not clear to me whether or not variable drawing surfaces are
supported by TIFF-FX. For example can I say that I support 2000x3000 pixels?
We have definitely agreed that we need to be able to do this as well as to
include the TIFF-FX defined, named set of drawing surfaces. It is not
supported by TIFF-FX and we need to create a profile that does support it.
> Its not clear from the issue whether variable drawing surfaces is a
REQUIRED or an OPTIONAL feature of a Printer. Which are we talking about?
> In talking with Lloyd McIntyre, he says that TIFF-FX does provide a way to
do variable drawing surfaces. Profile M has multiple layers. If the
background layer is given the desired resolution (and the other surfaces
have to have the same resolution), then any desired resolution can be
represented. However, I think that a device that doesn't understand the M
profile will try to display the mask layer not the background layer, so that
it might miss all of the important information that is now being conveyed in
the background layer. So there may be problems with using the M Profile to
get variable drawing surface.
This archive was generated by hypermail 2b29 : Mon Apr 23 2001 - 17:12:05 EDT