1.. index:: ! grdmix 2.. include:: module_core_purpose.rst_ 3 4****** 5grdmix 6****** 7 8|grdmix_purpose| 9 10Synopsis 11-------- 12 13.. include:: common_SYN_OPTs.rst_ 14 15**gmt grdmix** 16*raster1* [ *raster2* [ *raster3*]] 17|-G|\ *outfile* 18[ |-A|\ *alpha* ] 19[ |-C| ] 20[ |-D| ] 21[ |-I|\ *intensity* ] 22[ |-M| ] 23[ |-N|\ [**i**\|\ **o**][*divisor*] ] 24[ |-Q| ] 25[ |SYN_OPT-R| ] 26[ |SYN_OPT-V| ] 27[ |-W|\ *weights* ] 28[ |SYN_OPT-f| ] 29[ |SYN_OPT--| ] 30 31|No-spaces| 32 33Description 34----------- 35 36**grdmix** will perform various operations involving images and grids. 37We either use an *alpha* grid, image, or constant to add a new alpha 38(transparency) layer to the image given as *raster1*, or we will blend 39the two *raster1* and *raster2* (grids or images) using the *weights* for 40*raster1* and the complementary *1 - weights* for *raster2* and save to 41*outfile*. Alternatively, we will deconstruct an image into its component 42(red, green, blue or gray) grid layers or we construct an image from its 43normalized component grids. 44All operations support adjusting the final color image via an *intensity* 45grid, converting a color image to monochrome, or strip off the alpha layer. 46All *raster?*, *alpha*, *intensity* and *weights* files must have the same 47dimensions. The optional *alpha*, *intensity* and *weights* files may be 48replaced by constant values instead. 49 50Required Arguments 51------------------ 52 53*raster?* 54 If only one is given and **-C** is not set then *raster1* must be an image. 55 If two are given then *raster1* and *raster2* must both be either 56 images or grids. If three are given then they must all be grids and 57 **-C** must be set. 58 59.. _-G: 60 61**-G**\ *outfile* 62 The name for the output raster. For images, use one of these extensions: 63 tif (GeoTIFF), gif, png, jpg, bmp, or ppm. For grids, see 64 :ref:`Grid File Formats <grd_inout_full>`. 65 66Optional Arguments 67------------------ 68 69.. _-A: 70 71**-A**\ *alpha* 72 Get a constant alpha (0-1), or a grid (0-1) or image (0-255) with alphas. 73 The final image will have a transparency layer add based on these values. 74 75.. _-C: 76 77**-C** 78 **C**\ onstruct an output image from one or three normalized input grids; 79 these grids must all have values in the 0-1 range only (see **-Ni** if they don't). 80 Optionally, use **-A** to add transparency and **-I** to add intensity 81 to the colors before writing the image. For three layers the input order must 82 be red grid first, then the green grid, and finally the blue grid. 83 84.. _-D: 85 86**-D** 87 **D**\ econstruct a single image into one or three output grids. 88 An extra grid will be written if the image contains an alpha (transparency layer). 89 All grids written will reflect the original image values in the 0-255 range exclusively; 90 however, you can use **-No** to normalize the values to the 0-1 range. 91 The output names uses the name template given by **-G** which must contain the 92 C-format string "%c". This code is replaced by the codes R, G, B and A for color 93 images and g, A for gray-scale images. 94 95.. _-I: 96 97**-I**\ *intensity* 98 A constant intensity or grid (-1 to +1 range) to modify final output image colors. 99 100.. _-M: 101 102**-M** 103 Force conversion to monochrome image using the (television) YIQ 104 transformation. 105 106.. _-N: 107 108**-N**\ [**i**\|\ **o**][*divisor*] 109 Normalize all input grids from 0-255 to 0-1 and all output grids from 0-1 to 0-255. 110 To only turn on normalization for input *or* output, use **-Ni** or **-No** instead. 111 To divide by another value than 255, append an optional *divisor*. 112 113.. _-Q: 114 115**-Q** 116 Make the final image opaque by removing the alpha layer (if present). 117 118.. |Add_-R| replace:: |Add_-R_links| 119.. include:: explain_-R.rst_ 120 :start-after: **Syntax** 121 :end-before: **Description** 122 123.. |Add_-V| replace:: |Add_-V_links| 124.. include:: explain_-V.rst_ 125 :start-after: **Syntax** 126 :end-before: **Description** 127 128.. _-W: 129 130**-W**\ *weights* 131 A constant weight (0-1), or a grid (0-1) or image (0-255) with weights. 132 When two input rasters are given, the weights are applied to *raster1* and 133 (*1-weights*) are applied to *raster2*, then the products are summed. 134 135.. |Add_-f| unicode:: 0x20 .. just an invisible code 136.. include:: explain_-f.rst_ 137 138.. include:: explain_help.rst_ 139 140Examples 141-------- 142 143.. include:: explain_example.rst_ 144 145To blend the night and day views of the Earth using a weight image computed for 146a particular day/night terminus, try:: 147 148 gmt grdmix @earth_day_06m @earth_night_06m -W@weight.png -Gnewmap.png 149 150Suppose map1.png and map2.png are overlapping maps of different quantities, but we wish 151to use the image visible.png to blend them into a single image: Where visible.png has 152values close to 255 we will see predominantly the map1.png contents while for values 153closer to zero we will mostly see map2.png - values in between these extremes will 154lead to a weighted average. We try:: 155 156 gmt grdmix map1.png map2.png -Wvisible.png -Gnewmap.png -V 157 158To insert the values from the grid transparency.grd into the image gravity.tif as an alpha 159(transparency) layer, and write out a transparent PNG image, try:: 160 161 gmt grdmix gravity.tif -Atransparency.grd -Gmap.png 162 163To break the color image layers.png into separate, normalized red, green, and blue grids (and possibly an alpha grid), 164we run:: 165 166 gmt grdmix layers.png -D -Glayer_%c.grd -No 167 168To recombine the three normalized grids red.grd, green.grd, and blue.grd into a TIFF file, but 169applying intensities from intens.grd and add transparency from transp.grd grids, try:: 170 171 gmt grdmix red.grd green.grd and blue.grd -Glayer.tif -Atransp.grd -Iintens.grd 172 173 174See Also 175-------- 176 177:doc:`gmt`, :doc:`grdblend`, 178:doc:`grdclip`, 179:doc:`grdcut`, 180:doc:`grdinfo`, 181:doc:`grdsample` 182
