Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
Re: Exporting ENVI display to reduced reslution JPEG
On Mar 29, 12:22 pm, "Matt" <mmsmith1...@gmail.com> wrote: > I need to create over 300 reduced resolution JPEGS derived from > satellite data. Each JPEG contains between 100 and 5000 pixels with > values of 1 out of 35 million pixels with values of 0. When I create > the reduced resolution JPEG the 1 pixels are lost in the sea of 0 > pixels. > > So, I created a vector layer that has a point for each pixel with a > value of 1. I then overlay the vector on the image, and export the > result into a reduced resolution JPEG. I've gotten as far as creating > the vector layer, but haven't figured out if I can programmatically > export the 'scroll' display that I get. The help files haven't helped > me much. > > I have figured out that you can get a display number from ENVI once a > display is opened, which leads me to beleive that you could use this > number to export the image, but haven't found anything explicitly > stating this. > > Any suggestions on how I could go about exporting a reduced resolution > JPEG from a vector overlayed on a raster? Should I bypass ENVI all > together and work through IDL exclusively? Any input will be greatly > appreciated. > > thanks, > Matt I've never tried to do this but I think you can use ENVI_DISP_QUERY to get the window ID of the scroll window, WSET to that window ID, then do a TVRD() to get the contents. The thing I'm not sure of is why you decided to overlay vectors. If all you are trying to do is make pixels stand out better, aren't there better (easier) ways to do this? Jeff
On Mar 29, 4:32 pm, "Jeff N." <jnett...@utk.edu> wrote: > On Mar 29, 12:22 pm, "Matt" <mmsmith1...@gmail.com> wrote: > > > >> I need to create over 300 reduced resolution JPEGS derived from >> satellite data. Each JPEG contains between 100 and 5000 pixels with >> values of 1 out of 35 million pixels with values of 0. When I create >> the reduced resolution JPEG the 1 pixels are lost in the sea of 0 >> pixels. > >> So, I created a vector layer that has a point for each pixel with a >> value of 1. I then overlay the vector on the image, and export the >> result into a reduced resolution JPEG. I've gotten as far as creating >> the vector layer, but haven't figured out if I can programmatically >> export the 'scroll' display that I get. The help files haven't helped >> me much. > >> I have figured out that you can get a display number from ENVI once a >> display is opened, which leads me to beleive that you could use this >> number to export the image, but haven't found anything explicitly >> stating this. > >> Any suggestions on how I could go about exporting a reduced resolution >> JPEG from a vector overlayed on a raster? Should I bypass ENVI all >> together and work through IDL exclusively? Any input will be greatly >> appreciated. > >> thanks, >> Matt > > I've never tried to do this but I think you can use ENVI_DISP_QUERY to > get the window ID of the scroll window, WSET to that window ID, then > do a TVRD() to get the contents. The thing I'm not sure of is why you > decided to overlay vectors. If all you are trying to do is make pixels > stand out better, aren't there better (easier) ways to do this? > > Jeff Thanks Jeff. I don't have much experience with IDL so I think I was only able to come up with a practical solution when thinking inside a GIS framework. I imagine that there are easier solutions out there but this way I was able to see each step that I needed to take. I'm not knowledgeable enough in IDL to see other simpler solutions, so any suggestions are most welcome. In any case, thanks for the help, I will give it a try, Matt