Jump to content

 
Photo

Photoshop guru needed

- - - - -

  • Please log in to reply
3 replies to this topic

#1
David Medeiros

David Medeiros

    Hall of Fame

  • Validated Member
  • PipPipPipPipPipPipPip
  • 1,085 posts
  • Gender:Male
  • Location:Redwood City CA
  • Interests:Cartography, wood working, wooden boats, fishing, camping, overland travel, exploring.
  • United States

I need some photo shop help with a TIF DEM. I have a grayscale DEM that I'm trying to use with some CNC software. In order to have the CNC application read the DEM correctly I need to separate the base or ocean gray from the near shore gray a little more. Right now ocean is 100k with the near shore being 99k (too close to see in the CNC cut). I'd like to bump the near shore gray to 98k or even 96k. How do I do that in photoshop? I've played with every function I can find until my eyes have gone blurry. Need help!

Thanks,

dave

Attached Files


GIS Reference and Instruction Specialist, Stanford Geospatial Center.

 

www.mapbliss.com

 


#2
Peter Finch

Peter Finch

    Newbie

  • Validated Member
  • Pip
  • 4 posts
  • No Country Selected

Hi Dave,

Here is one way you can do it.
Go to Select --> Color Range... With the Eye Dropper tool select a sample from the ocean pixels (100k) then in the Color range dialogue box check the invert button. Click OK and all values below 100k are selected.
Next select Image --> Adjustments --> Levels, bringing up the levels dialogue box.
In the Output levels box changing 0 to 8 will shift the 99k values to 96k.

I hope this helps.

#3
l.jegou

l.jegou

    Master Contributor

  • Validated Member
  • PipPipPipPip
  • 114 posts
  • Gender:Male
  • Location:Toulouse
  • Interests:Webmapping, thematical mapping.
  • France

Hello, i'll try a selection by range and then some histogram levels (or curves) tweaking.

Select by range : http://livedocs.adob...1ab64-76f4.html

Levels : http://livedocs.adob...1ab64-7672.html

#4
Unit Seven

Unit Seven

    Legendary Contributor

  • Moderator
  • PipPipPipPipPip
  • 266 posts
  • Gender:Male
  • Location:New Zealand
  • New Zealand

You can bump using the values but IMO you are best to get a coastline in there to keep it all looking 'right'. Where should that 1m change to 0m elevation? how accurate is your DEM to the coastline etc.

If you can create a vector pdf to the exact extents of your DEM with white sea and black land or vice versa. Open this pdf in photoshop setting the pixel dimensions to be the same. You can then use this as a mask for an adjustment layer which you can use to bump all the land up.

If you need soem more info on this drop a line back here.

Cheers,
Sam
S a m B r o w n

U N I T S E V E N
unit.seven@gmail.com

Miramar, Wellington
N E W Z E A L A N D




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

-->