Requested Tiff overviews

[uclaros]

Hi,
when using large raster datasets in CAD and GIS software it is common to have overviews of the raster, each one being half the resolution of the previous, so that software can automatically load the required overview depending on the zoom level and not the full resolution image. This allows for fast loading and zooming-panning operations.
A common tool for building overviews is http://www.gdal.org/gdaladdo.html
Such Tiff internal overviews are identified by irfanview as pages in multi-page tiffs.
When such a tiff is opened in irfanview, page 1 is the full resolution raster, 2 is the half resolution, 3 is the 1/4 etc.
Usually, opening the full resolution raster just to display it subsampled at the screen resolution makes no sense
Full support for overviews when opening, zooming and panning such images in irfanview would be great but too much to ask for, so instead I believe the following would be a good and easy solution:
When opening a multipage tiff the default page loaded could be the overview that matches best the screen resolution. This could be enabled by an option that is off by default so that it does not break the current functionality.

Thanks for the great viewer!
Best regards

[Bhikkhu Pesala]

IrfanView can open multipage TIF files and pan, zoom etc., on any page without difficulty. Use the 64-bit version for faster opening of large images.

Set a shortcut with a command-line option to open those TIF files at page 2 or whatever suits your monitor resolution with this command line switch (see C:\Program Files\i_options.txt for all command-line switches)

"C:\Program Files\IrfanView\i_view64.exe" /page=2

/page=X - open page number X from a multipage input image

Edit: I tried this, but I could not get the file to open by dropping it onto my shortcut. Maybe someone with more experience of command-line switches can help you out.