I have some cpc precipitation data stored in IMG format.

Could anyone suggest a software beside ERDAS imagine or Arcgis which can be freely downloaded?

  • 7zip is also able to open img files. It also gives the option to extract them.
    – JoelSolo
    Jun 21, 2014 at 20:25
  • I notice that you have not accepted any of the answers offered. An alternative site within SE that you may want to consider when asking for software recommendations is Software Recommendations (beta).
    – PolyGeo
    Jun 29, 2014 at 3:48
  • 1
    .img is not enough to identify a format, it is ambiguous at best. Note that some software ignore the extension,or only use it as part of the evidence, and some formats ship without an extension at all
    – mdsumner
    Dec 24, 2014 at 20:40

3 Answers 3


GDAL supports .img format, both the basic Imagine and the extended Imagine (greater than 2GB), thus any software that utilizes GDAL drivers would support ERDAS Imagine.

The most workable and well documented that I have seen is QGIS. It is also open source and therefore free.

  • I have the latitude and longitude for the location and I need to extract data from that point on the image as shown here"i.imgur.com/uLwlb9l.png".I tried installing QGIS but couldn't figure out the steps to do this.Could you please explain.Can this be done on Erdas ER viewer.
    – shrey
    Jun 22, 2014 at 15:00
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    I'm really not sure. I have used QGIS and found it to be quite workable for vector but have not done any raster analysis in it. Generally speaking the site rules are one question per question, normally I wouldn't be too concerned about a follow-up question but in this case I think that you should post that as a second question.. start with New to QGIS, would like to know how to... otherwise that fairly important question may be lost in this thread. Jun 22, 2014 at 21:57
  • 3
    Technically Michael is right about 1 question per thread. However, the answer to your 'how to in qgis' question is already answered in many threads. Use the Point Sampling Tool (you may have to use the plugins menu to install it) Jun 23, 2014 at 8:12

The software to choose depends on your objectives.

For GIS purpose, QGIS is great. It includes many toolboxes for spatial analysis. It is an open source alternative to ArcGIS.

For image processing, you can use Monteverdi. Monteverdi is particularly usefull if you have very large images. It is an open source alternative to Erdas.


If you are looking for a free software there are several that can do that however I don't know how can they handle the CPC imagine files but ENVI 5.1 can open it and can read img files if that is what you are looking for. ENVI is not free but is another good software to have around. I have ERDAS, ArcGIS 10.1 and ENVI 5.0 and they all can open and read it. Not sure if the free software have the capability to handle CPC file.

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