[ERDAS-L:6418] Overlay one image over another

[ERDAS Communities - Automated Email]

Overlay one image over another
By technotracer in ERDAS Software Forum

Hello ERDAS Community :)

I am working with a grayscale raster file.  What I would like to do is "paint" pixels above a defined threshold with a specific colour (ie purple) and all other pixels should be transparent.   I would then like to overlay the selected purple pixels over the original grayscale image.  

If anyone knows how to do this in IMAGINE I would be grateful for some help.  

I am thinking the solution is to use Spatial modeler with a conditional statement to convert the image from continuous to thematic but not sure how to code it.  

Thank you for your help.

Cheers,

Rob

----------------------------------
You were sent this email because you opted to receive email notifications when someone created a new thread, or replied to a topic within this forum, ERDAS Software Forum.

To unsubscribe:

1. To unsubscribe from this item only, visit the item link and turn off notifications.
2. To stop all notifications of any updated items from ERDAS Communities, go to Edit Profile, click on the Site Options tab, then under Email Configuration, set Send Notifications to "No".

--
You received this message because you are subscribed to the Google Groups "ERDAS Communities Archive (formerly ERDAS-L Archive)" group.
To post to this group, send email to erdas-co...@googlegroups.com.
To unsubscribe from this group, send email to erdas-communit...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/erdas-communities?hl=en.

[ERDAS Communities - Automated Email]

Re: Overlay one image over another
By Donn Rodekohr in ERDAS Software Forum

Rob,

This would be a pretty simple model.  Say your grayscale threshold value is 249, write a model like this:

Input file:  $n1_bw

Function statement:  either (0 if ($n1_bw < 249) or 1 otherwise

Output file: $n2_purplehaze  defined as a 2 bit Thematic file

Open purplehaze in a viewer and open the raster attributes.  Assign an opacity value of 0 to 0, assign your favorite color of purple to 1 (and maybe an opacity value?).  Save you changes.

Now open the bw image and overlay purplehaze without clearing the viewer.  

If you want to alter the colors of your grayscale thematic file directly you can do it in two steps:

1.  View the BW image in a viewer.  Open Image Info and compute stats, making sure that the skip value is set 1,1.  Now Edit the themacity and change it to Thematic.

2.  Clear the viewer and re-read BW as a Thematic.  Open the raster attributes.  Right click on the Row and do a Criteria select where row >= 249.  Click on the color and set it to your favorite shade of purple.

Save the changes.

 

 

 

----------------------------------
You were sent this email because you opted to receive email notifications when someone responded to this thread.

To unsubscribe:

1. To unsubscribe from this item only, visit the item link and turn off notifications.
2. To stop all notifications of any updated items from ERDAS Communities, go to Edit Profile, click on the Site Options tab, then under Email Configuration, set Send Notifications to "No".