I have a number of tif files. These tif files have white background and black contours. What I want to achieve is to make this white background completely transparent. I tried a lot of gdalwarp commands, but to no avail:
gdalwarp -srcnodata 255 -dstalpha ... # completely transparent. See no image
gdalwarp -srcnodata 0 -dstalpha ... # completely transparent. See no image
gdalwarp -srcnodata 255 ... # has no effect
gdalwarp -srcnodata 0 ... # also has no effect
It seems like I tried all possible combinations, but to no effect.
What is wrong with that and how can I fix it?
If I run this command with one of my tif files:
gdal_translate -of VRT 1-A.tif color.vrt
I get this as an output:
....
<VRTRasterBand dataType="Byte" band="1">
<Metadata domain="IMAGE_STRUCTURE">
<MDI key="NBITS">1</MDI>
</Metadata>
<NoDataValue>255</NoDataValue>
<ColorInterp>Palette</ColorInterp>
<ColorTable>
<Entry c1="255" c2="255" c3="255" c4="255" />
<Entry c1="0" c2="0" c3="0" c4="255" />
</ColorTable>
<SimpleSource>
<SourceFilename relativeToVRT="1">1-A.tif</SourceFilename>
<SourceBand>1</SourceBand>
<SourceProperties RasterXSize="5990" RasterYSize="5995" DataType="Byte" BlockXSize="5990" BlockYSize="10" />
<SrcRect xOff="0" yOff="0" xSize="5990" ySize="5995" />
<DstRect xOff="0" yOff="0" xSize="5990" ySize="5995" />
</SimpleSource>
....
It seems like my tif has only two colors - black and white. And what I want to achieve with GDAL (if it is possible), is to make white color completly transparent, so that when I publish my layer, I would see just black contours. Indeed I do not want to use Photoshop and cut all white color from all dozens of tifs. I hope, it can be done massively, using GDAL.
If it matters, my WMS service, which publishes all my layers, is configured with transparent=true and "format=image/png". So, it seems like I tried absolutely everything, but failed.
Here is some new information. This is what gdalinfo returns about one of the tifs (the real world tif published by Geoserver using Pyramid plugin):
gdalinfo layer_537__01_01.tif
Driver: GTiff/GeoTIFF
Files: layer_537__01_01.tif
Size is 2054, 2054
Coordinate System is:
...
...
Pixel Size = (0.169359008116544,-0.169359008116544)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
INTERLEAVE=BAND
Corner Coordinates:
...
Band 1 Block=2054x3 Type=Byte, ColorInterp=Palette
Color Table (RGB with 256 entries)
0: 255,255,255,255
1: 0,0,0,255
2: 0,0,0,255
3: 0,0,0,255
4: 0,0,0,255
5: 0,0,0,255
6: 0,0,0,255
7: 0,0,0,255
8: 0,0,0,255
9: 0,0,0,255
10: 0,0,0,255
11: 0,0,0,255
...
I'm not sure, if it matters or not, but when I create the final mosaic with gdal_retile.py, I use co "COMPRESS=JPEG". I do not know if it can effect the initial transparency of the geotiff.
INPUT
This is a typical tiff that I have ^^^.
OUTPUT
And this is what I want to achieve ^^^. I tried trillions of gdalwarp and gdal_translate and even gdalbuildvrt parameters, but completely to no avail, though the task at first glance looks absolutely trivial.
Do you know all those GDAL commands that I should apply to my tiff?
PS
This is how I can solve this task using QGIS:
And this is exactly what I want to achieve manually, using GDAL.
Try # 1
In this attempt I try gdalbuildvrt like so:
$ gdalbuildvrt -srcnodata "255 255 255" -input_file_list tiles.txt mosaic.vrt
$ gdal_translate -co "TILED=YES" -co "BIGTIFF=YES" -co "NBITS=1" -co "COMPRESS=CCITTFAX4" mosaic.vrt layer.tiff
When I check mosaic.vrt, I see this contents:
<VRTRasterBand dataType="Byte" band="1">
<NoDataValue>255</NoDataValue>
<ColorInterp>Palette</ColorInterp>
<ColorTable>
<Entry c1="255" c2="255" c3="255" c4="255" />
<Entry c1="0" c2="0" c3="0" c4="255" />
<Entry c1="0" c2="0" c3="0" c4="255" />
<Entry c1="0" c2="0" c3="0" c4="255" />
<Entry c1="0" c2="0" c3="0" c4="255" />
...
<Entry c1="0" c2="0" c3="0" c4="255" />
</ColorTable>
And when I check layer.tiff with gdalinfo, I see this:
Driver: GTiff/GeoTIFF
Files: layer.tiff
Size is 11889, 11974
Coordinate System is:
...
Origin = ...
Pixel Size = (0.169326783070411,-0.169326783070411)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
COMPRESSION=CCITTFAX4
INTERLEAVE=BAND
Corner Coordinates:
Upper Left ...
Lower Left ...
Upper Right ...
Lower Right ...
Center ...
Band 1 Block=256x256 Type=Byte, ColorInterp=Palette
NoData Value=255
Image Structure Metadata:
NBITS=1
Color Table (RGB with 2 entries)
0: 255,255,255,255
1: 0,0,0,255
And this what I see, when I publish this tiff and visualize it on top of OpenStreetMap:
So, as you can see white color did't become transparent. And if it matters, these are parameters with which the layer is requested from WMS service:
So, this try again failed.
UPDATE
This is in fact what I want to achieve. I want to transform before.tiff to after.tiff (the way QGIS it did):
$ gdalinfo before.tiff
Driver: GTiff/GeoTIFF
Files: before.tiff
Size is 11889, 11974
Coordinate System is:
...
Origin = ...
Pixel Size = (0.169326783070411,-0.169326783070411)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
COMPRESSION=CCITTFAX4
INTERLEAVE=BAND
Corner Coordinates:
...
Band 1 Block=256x256 Type=Byte, ColorInterp=Palette
NoData Value=255
Image Structure Metadata:
NBITS=1
Color Table (RGB with 2 entries)
0: 255,255,255,255
1: 0,0,0,255
$ gdalinfo after.tiff
Driver: GTiff/GeoTIFF
Files: after.tiff
Size is 11889, 11974
Coordinate System is:
...
Origin = ...
Pixel Size = (0.169326783070424,-0.169326783070413)
Metadata:
AREA_OR_POINT=Area
Image Structure Metadata:
INTERLEAVE=PIXEL
Corner Coordinates:
...
Band 1 Block=11889x1 Type=Byte, ColorInterp=Red
Mask Flags: PER_DATASET ALPHA
Band 2 Block=11889x1 Type=Byte, ColorInterp=Green
Mask Flags: PER_DATASET ALPHA
Band 3 Block=11889x1 Type=Byte, ColorInterp=Blue
Mask Flags: PER_DATASET ALPHA
Band 4 Block=11889x1 Type=Byte, ColorInterp=Alpha
The most important part, that changed is Image Structure Metadata.
