Hermann, You're right the size difference is because of PNG8 or PNG24.
I'm now on the gdal_warp track again. But I can't produce a PNG file. When I use -ot PNG I get this list of supported file formats: VRT: Virtual Raster GTiff: GeoTIFF NITF: National Imagery Transmission Format HFA: Erdas Imagine Images (.img) ELAS: ELAS MEM: In Memory Raster BMP: MS Windows Device Independent Bitmap PCIDSK: PCIDSK Database File ILWIS: ILWIS Raster Map SGI: SGI Image File Format 1.0 Leveller: Leveller heightfield Terragen: Terragen heightfield ERS: ERMapper .ers Labelled JP2ECW: ERMapper JPEG2000 RMF: Raster Matrix Format RST: Idrisi Raster A.1 INGR: Intergraph Raster GSBG: Golden Software Binary Grid (.grd) PNM: Portable Pixmap Format (netpbm) ENVI: ENVI .hdr Labelled EHdr: ESRI .hdr Labelled PAux: PCI .aux Labelled MFF: Vexcel MFF Raster MFF2: Vexcel MFF2 (HKV) Raster BT: VTP .bt (Binary Terrain) 1.3 Format IDA: Image Data and Analysis ADRG: ARC Digitized Raster Graphics SAGA: SAGA GIS Binary Grid (.sdat) Does this mean I haven't build my GDAL properly? If not can you give me a hint on how to enable png support in the make files? Thanks, Paul 2010/10/26 Hermann Peifer <[email protected]> > On 25/10/2010 11:17, Paul Meems wrote: > >> Hi list, >> >> I've got several png files with worldfiles. >> I need them in another projection (28992 --> 3785). >> I'm using gdalwarp to reproject to a tiff file and then I use >> gdal_translate to create a png file again. >> My original png file is about 25 kB, the warped tiff is over 2MB and the >> translated png file is over 80 kB. >> >> > I am not quite sure why you don't use -of png to save the creation of the > intermediate tiff file. You might also be able to use -of byte which creates > an 8 bit PNG (if this format is sufficient for your purpose). > > The size difference 20k vs 80k could be due to the fact that the source > file is PNG8 and the generated file is PNG24. There may be other reasons, > though. > > Hermann >
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