Apply a linear stretch of the selected color table to the input grid between the maximum and minimum cell values. In this method, all cell values of the input raster grid are re-scaled into new values in the output grid.
To apply a linear transformation to the colors of the input raster:
- Select Linear from the Transform drop-down list.
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Select the Apply Clip Limits check-box to allow a specific range of cell values to be rendered, while blocking lower and higher cell values.
You will see the bandpass vertical bars on the histogram representing the upper and lower cutoff values. You can slide the bars to change the values. The vertical color bar showing the color distribution also changes with each slide. You will also see two check-boxes Show Mean and Show Std Dev. When you select the check-boxes, you will see the mean value and standard deviation of the color value distribution on the histogram. The mean value is represented by a vertical dotted line in the center of the graph. The standard deviations are represented by vertical dotted lines in orange, as shown in the image below.
From the graph, you can see that the standard deviations do not match with that in raster statistics. This is because the standard deviations are calculated based the mean value. For example, in an input raster, the range of values are from 1-100 (1 being the min and 10 being the max), the standard deviation is 10, and the mean is 50. The standard deviation lines will have the values 60 (50+(1*10)) and 70 (50+(2*10)) on the right side of the mean. On the left side of the mean, the standard deviations will be 40 (50-(1*10)) and 30 (50-(2*10)).
As you move the bandpass vertical bars to the right or left, the bandpass values will change according to the position of the bars on the histogram. The new bandpass values will be displayed in the Min Limit and Max Limit fields. You can also provide the minimum and maximum limits by entering the values in the respective input fields below the Histogram
In addition, you will also see the color distribution table beneath the histogram. If you hover over the histogram, the color bars on the table will change accordingly depending on the position of the mouse pointer. The table above shows the value of the bin at the mouse position as highlighted. It also shows value of two bins before and after the current cursor location.
- You can also manually change the bandpass values in the Min Limit and Max Limit fields. To view a zoomed-in version of the clipped area under the bandpass limits, click Zoom Limits. You will see a "mini" version of the original histogram clipped to the limits. Reset to the original histogram by clicking Reset Limits.
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Select the cutoff method from the Limits Specified As drop-down list. The list items represent various multi-value range methods.
The options in this drop-down list are:
- Absolute - The values of the output grid cells depend on the data range that each input grid cell value falls within. Upon selection of Absolute, you will see the values populated in the fields.
- Percentage - The output grid will depend on the percentage range that each input grid cell value falls within. Upon selection of Percentage, you will see the values populated in the fields.
- Percentile - The output grid will depend on the percentile range that each input grid cell value falls within. Upon selection of Percentile, you will see the values populated in the fields.
- Select the Clip limits to transparent check-box to make the areas outside the cutoff regions transparent.
- Click Apply Settings to apply the changes to the input raster and display it based on the parameters selected above.