Thanks- problem solved. Chas Sheeb On 17 January 2018 at 22:43, <qgis-user-requ...@lists.osgeo.org> wrote:
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(Michel Stuyts) > > > ---------- Forwarded message ---------- > From: Michel Stuyts <michel.stu...@edegem.be> > To: "qgis-user@lists.osgeo.org" <qgis-user@lists.osgeo.org> > Cc: > Bcc: > Date: Wed, 17 Jan 2018 14:33:03 +0000 > Subject: Re: [Qgis-user] Generating black white from RGB landsat using > Raster Map calculator? > > Chas, > > > > If I have a color GEOTIFF and I want to show or save it as a grayscale > GEOTIFF, I use one of these 2 solutions. Depending on the control you want > on the color to grayscale conversion it might also be a solution for you. > > > > > > Solution 1: > > If the only thing you want to do is show a colour geotiff in grayscale, > you can just change the properties of the layer. In the layer properties > you go to the tab “Style”. Under “Color rendering” you will find the option > “Grayscale”. By default the option will be set to “Off”, but you can change > it to turn grayscale on. Try one of the three options to see what fits your > image best. After that you can also change the values of “Brightness” or > “Contrast” to get the best result. > > > > This way you won’t change anything in your source file and it won’t save a > grayscale tiff, but it will just show your raster file as grayscale in QGIS. > > > > Solution 2: > > If you want to end up with a geotiff file that has the same information in > grayscale I usually use some graphical software in the process, but for > that you can’t use a GeoTiff, because you would loose the georeference > information of the file. Therefore I use the following steps: > > 1. Save your geotiff file as TIFF-file with a TFW file: > > a. Right click on your source geotiff file in the layers panel. > > b. Select Save As… > > c. Select Rendered image as Output Mode > > d. Select Gtiff as format > > e. Deselect “Add saved file to map” > > f. Under “Create Options” click on the + button to add an option. > For the newly added option you have to type TFW as “Name” and YES as > “Value” (double click in the newly created Option cell to type in it). > > g. Click on the “Browse…” button to select a name and location for > your grayscale TIFF file. > > h. Click on the “OK” button > > 2. Open the newly created TIFF file in graphical software like > XnView, IrfanView or GIMP. Change the image in that software to grayscale > and save the file. > > 3. Add the newly created TIFF file back to QGIS > > 4. Save your newly created TIFF file as a GeoTIFF file: > > a. Right click on your newly created TIFF file in the layers panel. > > b. Select Save As… > > c. Select Rendered image as Output Mode > > d. Select Gtiff as format > > e. Click on the “Browse…” button to select a name and location for > your grayscale GEOTIFF file. > > f. Click on the “OK” button > > > > Michel > > > > > > > > > > *Van:* Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] *Namens *Chas > Sheen > *Verzonden:* woensdag 17 januari 2018 14:33 > *Aan:* 'Micha Silver' <tsvi...@gmail.com>; qgis-user@lists.osgeo.org > *Onderwerp:* Re: [Qgis-user] Generating black white from RGB landsat > using Raster Map calculator? > > > > Mike, > > So everything in the capture below of the Raster calculator should work? I > cannot find any output. > > I’m in Perth, Australia so home now and away from the office and QGIS, but > would like to get it working tomorrow. > > How do apply a grayscale to a raster? As I said, I’m new to QGIS > > Chas Sheen > > > > *From:* Micha Silver [mailto:tsvi...@gmail.com] > *Sent:* Wednesday, January 17, 2018 8:39 PM > *To:* Chas Sheen <chassheen...@gmail.com>; qgis-user@lists.osgeo.org > *Subject:* Re: [Qgis-user] Generating black white from RGB landsat using > Raster Map calculator? > > > > Hello Chas > > On 01/17/2018 01:52 PM, Chas Sheen wrote: > > Richard, > > > > I should have made my initial query clearer. > > I am trying to output a black and white geotiff. > > It's still not clear what you are asking. AFAIK, there's no such thing as > a "black and white geotiff". You can apply any color table you want to any > raster. You can apply a gray scale to any of the landsat bands. > > > > If you are trying to create a new raster from the three RGB bands using > some expression, that should work. You can use either of three tools: the > built in QGIS raster calculator, or thru the Processing toolbox there's > SAGA Raster calculus and the GRASS module r.mapcalculator. > > > > Again, none of this has anything to do with coloring. After running the > raster calculator, you can color the result with a gray scale color table, > a red color table, or any other color ramp you choose. > > > > > > Have split the original (landsat) image into RGB images. > > When I apply the expression in the capture below, and hit run, nothing is > saved to the results directory. > > I’m assuming that my expression or something else in the raster calculator > is wrong? > > The final product that I’m after is a xyz grid where z is the black-white > amplitude…which I think should be relatively easy (?) once I have the > black-white image. > > After you running the calculator expression, then you can save the result > in many formats, including gridded XYZ, ArcINFO ASCII, or many others, > using the gdal_translate tool. This is under the Raster->Conversion menu. > > > > > > Chas Sheen > > 0448017282 > > > > *From:* Richard McDonnell [mailto:richard.mcdonn...@opw.ie > <richard.mcdonn...@opw.ie>] > *Sent:* Wednesday, January 17, 2018 7:13 PM > *To:* Chas Sheen <chassheen...@gmail.com> <chassheen...@gmail.com>; > qgis-user@lists.osgeo.org > *Subject:* Re: [Qgis-user] Generating black white from RGB landsat using > Raster Map calculator? > > > > Chas, > Two options for splitting RGB into separate images in QGIS. > > 1. Semi-Automatic Classification Plugin, Preprocessing, Split Raster > Bands > 2. Grass r-rgb (Processing Toolbox) > > Any one of these tools will split the Raster for you easy enough > Regards, > > Richard > > On 17/01/2018 00:48, Chas Sheen wrote: > > I split the image into R, G, B > > Worked out in QGIS wher the Raster map calculator is. > > Run...several times > > No result foud in Results Directory. It runs quickly then refreshes inputs > and logs to blanks. > > I'm new to QGIS....so have probably left out something basic. > > Any clues > > > > [image: Displaying image.png] > > > > > _______________________________________________ > > Qgis-user mailing list > > Qgis-user@lists.osgeo.org > > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > > > -- > *Richard McDonnell* > *GIS Specialist PgD GIS AssocSCSI* > *OPW FRM Data Management* > *52 Stephens Green, Dublin 2.* > TEL: 01 6476543 > > [image: Afbeelding verwijderd door afzender.] <http://www.opw.ie/> > > > > Email Disclaimer: http://www.opw.ie/en/disclaimer/ > > > > _______________________________________________ > > Qgis-user mailing list > > Qgis-user@lists.osgeo.org > > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user > > > > -- > > Micha Silver > > Ben Gurion Univ. > > Sde Boker, Remote Sensing Lab > > cell: +972-523-665918 > > > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user >
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