Thanks, you helped me a lot In my example, I have printed an area of aproximately 1km wide on an A4 Landscape that is 29,7cm wide, so 1inch is about 85.5m. So that should be the reason? :-)
regards, dejan "Rahkonen Jukka" <[EMAIL PROTECTED]> wrote on 31.07.2008 11:00:15: > Hi, > > What are the dimensions of the image you have captured in real world > utits? Your original aerial images have half a metre pixel size. > It mean that at 300 dpi one original image pixel corresponds with > one pixel at paper if square inch on your printout is presenting > exactly 150 by 150 meters in nature. That is the maximum quality > you can achieve. If square inch on paper equals to 75 by 75 meters > the maximum quolity is achieved already at 150 dpi. Multiplicating > original image pixels for printing cannot improve the quality. But > if you have zoomed out so far that creating output image means > downsampling the original imagery you should see the differense. > So, if your 2150x1111 low resolution image is covering a > considerably larger area than 1075x555 meters in real world it > should look better when downloaded at 300 dpi with 4300x2222 pixels. > > -Jukka Rahkonen- > > > > Lähettäjä: [EMAIL PROTECTED] [mailto: > [EMAIL PROTECTED] Puolesta [EMAIL PROTECTED] > Lähetetty: 31. heinäkuuta 2008 9:32 > Vastaanottaja: mapserver-users@lists.osgeo.org > Aihe: Re: [mapserver-users] Output image resolution - explanation needed > > Thanks Steve > > I still (unfortunatelly) don't understand why I am getting the "same > quality" image on the paper with the first and second print (the > second image has twice more pixels). Is it because of the input > image itself? To be specific - the raster input is aerial image that > gdalinfor reports as: > > Driver: GTiff/GeoTIFF > Files: 5C14-05-DOF.tif > Size is 4500, 6000 > Coordinate System is `' > Origin = (5419000.154658853100000,4964998.794652804700000) > Pixel Size = (0.499829146050620,-0.499829146050620) > Corner Coordinates: > Upper Left ( 5419000.155, 4964998.795) > Lower Left ( 5419000.155, 4961999.820) > Upper Right ( 5421249.386, 4964998.795) > Lower Right ( 5421249.386, 4961999.820) > Center ( 5420124.770, 4963499.307) > Band 1 Block=256x256 Type=Byte, ColorInterp=Red > Overviews: 2250x3000, 1125x1500, 563x750, 282x375 > Band 2 Block=256x256 Type=Byte, ColorInterp=Green > Overviews: 2250x3000, 1125x1500, 563x750, 282x375 > Band 3 Block=256x256 Type=Byte, ColorInterp=Blue > Overviews: 2250x3000, 1125x1500, 563x750, 282x375 > > regards, dejan > > "Steve Lime" <[EMAIL PROTECTED]> wrote on 30.07.2008 21:13:55: > > > Resolution in MapServer-speak is referring to the resolution of the > > output device a map > > will be displayed on. The value is used for scale computations and > > nothing else. It does not > > affect the size (in pixels) of MapServer. Scale values do impact the > > size at which features > > and text are rendered IF scaling (via SYMBOLSCALE) is turned on. > > Higher quality output is > > usually a matter of having more pixels to print, however you usually > > want larger features > > too which is where the resolution parameter combined with scaling can help. > > > > Steve > > > > >>> On 7/30/2008 at 2:21 AM, in message > > <[EMAIL PROTECTED]>, > > <[EMAIL PROTECTED]> wrote: > > > Hi, > > > > > > I am trying to download a high resolution image and print it on > a paper. I > > > am using p.mapper and its download function that enables downloading the > > > map image on different resolutions. > > > > > > I have turned on my raster layer (ortophoto image). I have > zoomed in to an > > > area of interest. I have downloaded the map twice - with a resolution of > > > 150 and 300. The image is shown i a new page/tab (firefox). I right click > > > on the image and save it as a png (also tried with a jpeg) file.Now, the > > > first file is 2150x1111 pixels, 120 dpi vertical and horizontal > resolution > > > (right click on a file, properties, summary, what does it mean?), the > > > second file is 4300x2222 pixels, 120 dpi vertical and horizontal > > > resolution. Seems ok. The second image is "doubled" in pixel size. > > > > > > Now, when I try to print this image on A4 paper, using 300dpi, the images > > > are the same, there is no "better quality" in second image. > > > > > > I have just finshed reading the Mapserver thread on "Change image > > > resolution in mapfile". Several limitations are mentioned there - max. > > > image size supported by Mapserver, "resolution" value/tag embedded in > > > output format, etc. Can it be related to my problem? Or is it maybe that > > > software I am using to print this image doesn't "use" this extra pixels? > > > Or I am just missing some basic stuff I need to know :-( > > > > > > > > > thanks very much on any explanation > > > > > > regards, dejan > >
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