Raster histogram

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(→‎Using Layer Properties)
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Click on {{button|text=Pref/Actions}} and deactivate ''Draw as lines''. Activate ''Show selected band'' and ''Always show min/max markers''.
 
Click on {{button|text=Pref/Actions}} and deactivate ''Draw as lines''. Activate ''Show selected band'' and ''Always show min/max markers''.
 
The value range of the selected band data is evenly divided into bins. The histogram shows how many pixels of the image fall into each of the bins (Figure '''B''')[[File: Qgis_histogram_singleband.png|thumb|right|200px|'''Figure B:''' Histogram of a single selected band]]. Click on [[File: Qgis_save_icon.png|20px]]. The graphics may be saved as png file.
 
The value range of the selected band data is evenly divided into bins. The histogram shows how many pixels of the image fall into each of the bins (Figure '''B''')[[File: Qgis_histogram_singleband.png|thumb|right|200px|'''Figure B:''' Histogram of a single selected band]]. Click on [[File: Qgis_save_icon.png|20px]]. The graphics may be saved as png file.
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== Using R scripts ==
 
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# If the processing toolbox is not visible, select {{mitem|text=Processing --> Toolbox}}.
 
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# In the processing toolbar, type {{typed|text=Get R scripts}} into the search field and click to open it. In the ''Install scripts and model windows'' unfold the folder ''Not installed'' and activate ''Advanced histogram'' as shown below in the screenshot. Click {{button|text=OK}}.
 
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[[File:Qgis_Get_Rscripts.png|200px]].
 
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# In the processing toolbar, type {{typed|text=Get R scripts}} into the search field and click to open the diaolog window. Specify the Input raster Layer and click the button {{button|text=...}} on to select the path and filename for the output graphics file. Click {{button|text=Run}}.
 
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[[File:Qgis_advanced_histogram.png|400px]].
 
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Be patient and have a look on the messages in the log window as some additional R packages need to be downloaded. The resulting graphics shows all histograms side by side.
 
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[[File:histogram_result.png|400px]]
 
 
[[Category: Working with Raster Data]]
 
[[Category: Working with Raster Data]]

Revision as of 19:30, 21 October 2018

Using Layer Properties

  1. Click Click the Open Data Source Manger QGIS 3.0 datasource.png and then Add raster layer QGIS 2.0 addrast.png and select the file /geodata/raster/s2/Subset_S2A_MSIL2A_20170619T_MUL.tif.
  2. After clicking Open , the raster layer appears on the QGIS canvas.
  3. Right click the layer name in the Layers panel and select Properties --> Histogram
  4. Click Compute Histogram. A histogram for all bands is displayed (Figure A). Left click and drag a box on the diagram to zoom in.
    Figure A: Line histograms of all bands

Click on Pref/Actions and deactivate Draw as lines. Activate Show selected band and Always show min/max markers.

The value range of the selected band data is evenly divided into bins. The histogram shows how many pixels of the image fall into each of the bins (Figure B)
Figure B: Histogram of a single selected band
. Click on Qgis save icon.png. The graphics may be saved as png file.
Retrieved from "http://wiki.awf.forst.uni-goettingen.de/wiki/index.php?title=Raster_histogram&oldid=14606"
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