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I want to take an image file (eg tiff) and convert it to a spreadsheet (csv, or whatever) such that each pixel becomes a cell with a numeric value for that pixel.

I have googled it, and everyone is trying to sell me OCR software, that is certainly not what I want.

I will be editing the image beforehand, so can convert it to any format required, and can crop it down to a managable size.

It's mainly greyscale I'm interested in, and could do the little bit of colour that I will need as 3 separate files (one per colour channel) .

I will be doing statistical analysis on the spreadsheet later. I could likelly knock somthing together in java to do it, especially given that this is a proof of concept for a (much) later programming project, but that really feels like far too much hastle for what should be a simple task.

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If you say you can do Java, why not. It's not too much of an overhead, although other programming languages could probably do it in less lines of code. I don't think you'll get a readymade solution for this. You can take a look at ImageMagick's interfaces for different programming languages. –  slhck Jun 4 '11 at 10:41
    
I'll just put this as a comment unless you ask for it as an answer, but using python and the PIL library. you can get to a pixel value in 3 lines of code 1) Import the library 2) open the file 3) getpixel. Everything else is just bookkeeping. –  Dennis Jun 4 '11 at 11:10
    
Having no idea what python code even looks like let alone how to code it, I personally will give that one a miss, but I'm sure it may work well for others. I am currently in the middle of finding a java editor so I can see if I can remeber how to use it. –  Thingomy Jun 5 '11 at 14:32

2 Answers 2

up vote 1 down vote accepted

It's not too complicated. Here's an approach in Java. You'd just need to write this to CSV.. just simple writing to a file.

for (int x = 0; x < image.getWidth(); ++x)
  for (int y = 0; y < image.getHeight(); ++y) {
    int pixel = image.getRGB(x, y);
    int r = (pixel >> 16) & 0xff;
    int g = (pixel >> 8) & 0xff;
    int b = (pixel) & 0xff;
  }
}

where image is a BufferedImage. You can load a BufferedImage with ImageIO.read(File input);. You'll find this in javax.imageio.ImageIO.

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This would certainly do the trick, it's been a long time since I've done any java though... –  Thingomy Jun 4 '11 at 11:09

I would try to use free open-source SAGA GIS, load your image with Module/File/Grid/Import/Image - you will get SAGA grid which you can export as XYZ file which is in fact text file containing X and Y values and the Z grid value of each pixel. This should be waht you neet. SAGA is free. :-) http://www.saga-gis.org/en/index.html

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