Factorize the Min and Max value settings group

source/docs/user_manual/working_with_raster/raster_properties.rst

@@ -120,9 +120,21 @@ Multiband color
 
 With the multiband color renderer, three selected bands from the image will be
 rendered, each band representing the red, green or blue component that will be
-used to create a color image. You can choose several :guilabel:`Contrast
-enhancement` methods: 'No enhancement', 'Stretch to MinMax', 'Stretch and clip
-to MinMax' and 'Clip to min max'.
+used to create a color image. QGIS automatically fetches for each band its
+:guilabel:`Min` and :guilabel:`Max` values over the whole raster and scale
+the coloring accordingly but you can control the values range with the help
+of the :ref:`Min/Max Value Settings <minmaxvalues>` section.
+
+A :guilabel:`Contrast enhancement` method can also be applied to the values:
+'No enhancement', 'Stretch to MinMax', 'Stretch and clip to MinMax' and 'Clip to min max'.
+
+.. index:: Contrast enhancement
+
+.. note:: **Contrast enhancement**
+
+   When adding GRASS rasters, the option *Contrast enhancement* will always be
+   set automatically to *stretch to min max*, regardless of if this is set to
+   another value in the QGIS general options.
 
 .. _figure_raster_multiband:
 
@@ -131,38 +143,15 @@ to MinMax' and 'Clip to min max'.
 
    Raster Symbology - Multiband color rendering
 
-This selection offers you a wide range of options to modify the appearance
-of your raster layer. First of all, you have to get the data range from your
-image. This can be done by choosing the :guilabel:`Extent` and pressing
-:guilabel:`Load`. QGIS can |radioButtonOn| :guilabel:`Estimate (faster)` the
-:guilabel:`Min` and :guilabel:`Max` values of the bands or use the
-|radioButtonOff| :guilabel:`Actual (slower)` :guilabel:`Accuracy`.
-
-Now you can scale the colors with the help of the :guilabel:`Load min/max values`
-section. A lot of images have a few very low and high data. These outliers can be
-eliminated using the |radioButtonOn| :guilabel:`Cumulative count cut` setting.
-The standard data range is set from 2% to 98% of the data values and can be adapted
-manually. With this setting, the gray character of the image can disappear.
-With the scaling option |radioButtonOff| :guilabel:`Min/max`, QGIS creates a color
-table with all of the data included in the original image (e.g., QGIS creates
-a color table with 256 values, given the fact that you have 8 bit bands).
-You can also calculate your color table using the |radioButtonOff| :guilabel:`Mean
-+/- standard deviation x` |selectNumber|.
-Then, only the values within the standard deviation or within multiple standard deviations
-are considered for the color table. This is useful when you have one or two cells
-with abnormally high values in a raster grid that are having a negative impact on
-the rendering of the raster.
-
-All calculations can also be made for the |radioButtonOff| :guilabel:`Current` extent.
-
 
 .. tip:: **Viewing a Single Band of a Multiband Raster**
 
    If you want to view a single band of a multiband
    image (for example, Red), you might think you would set the Green and Blue
-   bands to "Not Set". But this is not the correct way. To display the Red band,
-   set the image type to 'Singleband gray', then select Red as the band to use
-   for Gray.
+   bands to :guilabel:`Not Set`. But this is not the correct way. To display the Red band,
+   set the image type to :ref:`Singleband gray <singleband_gray>`, then select Red
+   as the :guilabel:`Gray band` to use.
+
 
 .. _paletted:
 
@@ -183,26 +172,19 @@ The label appears in the legend of the raster layer then.
 
    Raster Symbology - Paletted Rendering
 
-.. index:: Contrast enhancement
-
-**Contrast enhancement**
-
-.. note::
-   When adding GRASS rasters, the option *Contrast enhancement* will always be
-   set automatically to *stretch to min max*, regardless of if this is set to
-   another value in the QGIS general options.
 
 .. _singleband_gray:
 
 Singleband gray
 ...............
 
-This renderer allows you to render a single band layer with a :guilabel:`Color gradient`:
-'Black to white' or 'White to black'. You can define a :guilabel:`Min`
-and a :guilabel:`Max` value by choosing the :guilabel:`Extent` first and
-then pressing :guilabel:`Load`. QGIS can |radioButtonOn| :guilabel:`Estimate (faster)`
-the :guilabel:`Min` and :guilabel:`Max` values of the bands or use the
-|radioButtonOff| :guilabel:`Actual (slower)` :guilabel:`Accuracy`.
+This renderer allows you to render a single band layer with a :guilabel:`Color
+gradient`: 'Black to white' or 'White to black'. You can define a range of values
+to color other than the default :guilabel:`Min` and :guilabel:`Max` values of the
+whole raster, thanks to the :ref:`Min/Max Value Settings <minmaxvalues>` option.
+
+Again, a :guilabel:`Contrast enhancement` method can be applied to the values:
+'No enhancement', 'Stretch to MinMax', 'Stretch and clip to MinMax' and 'Clip to min max'.
 
 .. _figure_raster_gray:
 
@@ -212,19 +194,6 @@ the :guilabel:`Min` and :guilabel:`Max` values of the bands or use the
    Raster Symbology - Singleband gray rendering
 
 
-With the :guilabel:`Load min/max values` section, scaling of the color table
-is possible. Outliers can be eliminated using the |radioButtonOn| :guilabel:`Cumulative
-count cut` setting.
-The standard data range is set from 2% to 98% of the data values and can
-be adapted manually. With this setting, the gray character of the image can disappear.
-Further settings can be made with |radioButtonOff| :guilabel:`Min/max` and
-|radioButtonOff| :guilabel:`Mean +/- standard deviation x` |selectNumber|.
-While the first one creates a color table with all of the data included in the
-original image, the second creates a color table that only considers values
-within the standard deviation or within multiple standard deviations.
-This is useful when you have one or two cells with abnormally high values in
-a raster grid that are having a negative impact on the rendering of the raster.
-
 .. index:: Color map, Color interpolation, Discrete
 .. _label_colormaptab:
 
@@ -242,35 +211,12 @@ You can also create individual color maps for the single bands here.
    Raster Symbology - Singleband pseudocolor rendering
 
 
-Three types of color interpolation are available:
-
-#. Discrete
-#. Linear
-#. Exact
+Using a :guilabel:`Band` of the layer and its :ref:`values range set <minmaxvalues>`,
+three types of color :guilabel:`Interpolation` are available:
 
-You can choose the band on which QGIS will render the layer, then define
-a :guilabel:`Min` and :guilabel:`Max` value.
-
-Defining :guilabel:`Min/Max` values can be done with the help of the :guilabel:`Load min/max values` section.
-A lot of images have a few very low and high data. These outliers can be eliminated
-using the |radioButtonOn| :guilabel:`Cumulative count cut` setting. The standard
-data range is set from 2% to 98% of the data values and can be adapted manually.
-
-With this setting, the gray character of the image can disappear.
-With the scaling option |radioButtonOn| :guilabel:`Min/max`, QGIS creates a color
-table with all of the data included in the original image (e.g., QGIS creates a
-color table with 256 values, given the fact that you have 8 bit bands).
-You can also calculate your color table using the |radioButtonOn| :guilabel:`Mean +/-
-standard deviation x` |selectNumber|.
-Then, only the values within the standard deviation or within multiple standard deviations
-are considered for the color table.
-
-In the next part, :guilabel:`Interpolation` allows you to choose which
-interpolation mode to use between:
-
-* Discrete (a <= symbol appears in the value column);
-* Linear;
-* Exact (an equal symbol appears in the Value column);
+* Discrete (a <= symbol appears in the value column)
+* Linear
+* Exact (an equal symbol appears in the Value column)
 
 The :guilabel:`Color ramp` drop down list lists the color ramp in your QGIS. You
 can add a new one, edit or save the one you changed. The name of the color ramp
@@ -300,6 +246,53 @@ defined color table for other sessions.
 The |checkbox| :guilabel:`Clip out of range values` allows QGIS to not render pixel
 greater than the :guilabel:`Max` value.
 
+
+.. _minmaxvalues:
+
+Setting the min and max values
+..............................
+
+By default, QGIS reports the :guilabel:`Min` and :guilabel:`Max` values of the band(s)
+of the raster. A lot of images have a few very low and high data which can have a
+negative impact on the rendering of the raster. The :ref:`Min/Max Value Settings
+<minmaxvalues>` menu helps you control the values to render.
+
+.. _figure_raster_minmaxvalues:
+
+.. figure:: img/rasterMinMaxValues.png
+   :align: center
+
+   Raster Symbology - Min and Max Value Settings
+
+
+Available options are:
+
+* |radioButtonOff| :guilabel:`User defined`: Allows to manually override the default
+  :guilabel:`Min` and :guilabel:`Max` values of the band(s)
+* |radioButtonOff| :guilabel:`Cumulative count cut`: Removes the outliers data.
+  The standard data range of the data values is set from ``2%`` to ``98%`` and can
+  be adapted manually. With this setting, the gray character of the image can disappear.
+* |radioButtonOn| :guilabel:`Min/max`: Creates a color table with all of the
+  data included in the image (e.g., QGIS creates a color table with 256 values,
+  given the fact that you have 8 bit bands).
+* |radioButtonOff| :guilabel:`Mean +/- standard deviation x`: Creates a color
+  table that only considers values within the standard deviation or within multiple
+  standard deviations. This is useful when you have one or two cells with abnormally
+  high values in a raster grid that are having a negative impact on the rendering
+  of the raster.
+
+Calculations of the min and max values of the bands are made based on the:
+
+* :guilabel:`Statistics extent`: it can be :guilabel:`Whole raster`,
+  :guilabel:`Current canvas` or :guilabel:`Updated canvas`
+* and the :guilabel:`Accuracy`, which can be either :guilabel:`Estimate (faster)`
+  or :guilabel:`Actual (slower)`.
+
+.. note:: For some settings, you may need to press the :guilabel:`Apply` button of
+  the layer properties dialog in order to display the actual min and max values
+  in the widgets.
+
+
 Color rendering
 ---------------