Transparency color problem in Raster Design 2006

[Anonymous]

Currently running Raster Design 2006 sp1 on Acad2006 sp1. This is a recent upgrade from Acad 2004 & RD2004. Having a problem or maybe a misunderstanding on how transparency color is working on RD06. I need to crop 2 images polygonally and merge them along a common seamline (a polyline) which I crop both images with.

This is part of my work for a long time. With previous versions of RD and CO, I completed this task by increasing the image brightness by 1 in histogram so color 0 (black or no data) pixels are all color 1, then cropped the image. Wedges created at non aligned crop boundaries are filled with color 0 pixels. Then I picked the wedges as transparency color and merged the images. The final image was perfect and continuous.

Raster Design 2006 however does not seem to work in the same fashion. In histogram, the image has 0 frequency for color 0 so I went ahead and cropped the image, there were wedges created but when I ran histogram again, there were still 0 frequency on color 0. I went ahead anyways and picked the wedge as transparency color but some of the pixels on the data part of the image (black text) are also transparent on print.

Obviously the wedges are not color 0 but what color is the wedges? Is that how RD06 works now?

For this time, I could get around by merging the images then turn the transparency off because the images are small. However, I need a long term solution. Sometimes I don't want to merge the images because they are hugh already individually and I don't want to create a gigantic image.

The only thing I can think of is that I cropped the images on another machine without sp1 applied yet to RD06. Could that be the problem since RD sp1 addressed a problem with transparency color? Must I redo all the cropping on a machine with sp1 already applied? Need help.


Thanks in advance.

[Anonymous]

On Sun, 24 Sep 2006 18:29:49 +0000, derek lai <> wrote:

>Currently running Raster Design 2006 sp1 on Acad2006 sp1. This is a recent upgrade from Acad 2004 & RD2004. Having a problem or maybe a misunderstanding on how transparency color is working on RD06. I need to crop 2 images polygonally and merge them along a common seamline (a polyline) which I crop both images with.
>
>This is part of my work for a long time. With previous versions of RD and CO, I completed this task by increasing the image brightness by 1 in histogram so color 0 (black or no data) pixels are all color 1, then cropped the image. Wedges created at non aligned crop boundaries are filled with color 0 pixels. Then I picked the wedges as transparency color and merged the images. The final image was perfect and continuous.
>
>Raster Design 2006 however does not seem to work in the same fashion. In histogram, the image has 0 frequency for color 0 so I went ahead and cropped the image, there were wedges created but when I ran histogram again, there were still 0 frequency on color 0. I went ahead anyways and picked the wedge as transparency color but some of the pixels on the data part of the image (black text) are also transparent on print.
>
>Obviously the wedges are not color 0 but what color is the wedges? Is that how RD06 works now?
>
>For this time, I could get around by merging the images then turn the transparency off because the images are small. However, I need a long term solution. Sometimes I don't want to merge the images because they are hugh already individually and I don't want to create a gigantic image.
>
>The only thing I can think of is that I cropped the images on another machine without sp1 applied yet to RD06. Could that be the problem since RD sp1 addressed a problem with transparency color? Must I redo all the cropping on a machine with sp1 already applied? Need help.

Search the help file for "RBACKGROUND"

Changing the Transparency Color of an Image

You can make one color in each image transparent.

Making a color transparent is helpful if you want to see information
that is displayed behind the image. In a bitonal image, the
transparency color is always the background color of the image. For
grayscale and color images, you can choose the transparency color.

The transparency color is also used to replace data that is removed
when you edit an image using the rub or crop commands. If transparency
is turned on for the image, the rubbed areas (or the slack space in a
cropped image) become transparent. For more information, see Cropping
Images and Removing (Rubbing) Images.

If you merge two images, the transparency color that is used to fill
the space between the two images depends upon the display order you
specify in the Image Manager Toolspace . The Image Merge Images
option uses the transparency color of the first image in the list for
the fill color.

Sometimes you may want to designate an unused color as the
transparency color. For instance, when merging images, turning on
transparency may make some desirable pixels transparent. The
rbackground command allows you to designate an unused color in a
grayscale image as the transparency color. Pixels with a value of 255
(white) are changed to a value of 254 (near white), then the
transparency color is set to a value of 255. The resulting image will
have no pixels with a value of 255.

NoteChanging the transparency color does not affect the color of the
existing rubs and crops.

Phil Daley