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Occasional Contributor
Posts: 11
Registered: ‎05-18-2020

Export to which file to reduce image file size suggest ?

What is good to export an image from large file size to reduce ?  I have two images that are really huge and it can use up space...

This is my second profile.
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Technical Evangelist
Posts: 690
Registered: ‎02-02-2016

Re: Export to which file to reduce image file size suggest ?

Hi Robert,

 

I would suggest exporting your images to ECW format. Please review the documentation linked below for more information about the ECW file format.

 

Export Data to ECW - Workflow

 

ECW Format


Determine Compression Rates

 

Kind regards,

 

Stephen Bent

Hexagon Geospatial Support

 

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Occasional Contributor
Posts: 11
Registered: ‎05-18-2020

Re: Export to which file to reduce image file size suggest ?

Thanks for the information..

 

I'm curious ... Is it okay if I re-export to TIFF from ECW to preseve the ratio or is it going to revert to large file size ? 

This is my second profile.
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Technical Evangelist
Posts: 690
Registered: ‎02-02-2016

Re: Export to which file to reduce image file size suggest ?

Hi Robert,

 

The image is going to revert to it’s large file size if you convert from ECW format back to TIFF. If you really want to use the TIFF format you could use LZW or PackBits compression, but neither of these compression methods will come anywhere close to ECW.

 

Kind regards,

 

Stephen

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Technical Evangelist
Posts: 1,026
Registered: ‎10-01-2015

Re: Export to which file to reduce image file size suggest ?

If you want a lossless compression JPEG 2000 is a good robust technique to use. It also supports lossy if that's the way you want to go. 

Ian Anderson
Chief Product Owner, Desktop Remote Sensing
Hexagon Geospatial
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Contributor
Posts: 30
Registered: ‎12-06-2017

Re: Export to which file to reduce image file size suggest ?

I was able to do export a hillshade into ECW ; however in ArcGIS arcatalog showed me there is two subfiles that it came with it

 

AllOpacity and Grayscale .  The AllOpacity showed me light blue color but the Grayscale looks fine.

 

Is there a way around to turn the AllOpacity off ?

 

Thanks

Highlighted
Technical Evangelist
Posts: 1,026
Registered: ‎10-01-2015

Re: Export to which file to reduce image file size suggest ?

Hi @Robert1968 ,

 

As far as I know ERDAS IMAGINE always create the opacity channel when creating ECW v3 files. You almost always need it because ECW is a lossy compression so "background" generally becomes "not background" and the opacity channel is used to re-mask that. It also takes up virtually no additional space because it's only 1-bit (and losslessly compressed).

 

Is the opactiy channel causing a problem?

 

Cheers

Ian Anderson
Chief Product Owner, Desktop Remote Sensing
Hexagon Geospatial