[Qgis-developer] raster visualization

[Andrea Peri]

>- on initial load of a raster, generate a quicklook that is the larger
>of 1/4 screen resolution or 500x500 pixels by sampling every nth pixel
>- generate a histogram from the quicklook
>- calculate clipped 2% - 96% range min max for each band
>- apply a histogram stretch based on the above
>- the histogram could be used for generating the graph in raster
>props, and the quicklook could be used to create thumbs and previews
>etc
>- ideally we should cache these quicklooks and only regenerate them if
>the underlying dataset has changed
>
>I believe if we do this we will have fast initial load and the images
>(grayscale and rgb) will 'look right' when first loaded (i.e with good
>contrast) and it would not be necessary to assign any color value to
>grayscales by default.
>
>Regards

Hi,
just my 2 ct.

I guess the more important capability with raster is to open they faster
possible.

I fear calculate all these values on first opened take more time than what
is waitable for the open of a raster.

Perhaps this action should be choosable by settings ?

Of course I see our situation.

Our situation is of more sets of raster (7-800 each set) where every raster
is grey level or true color of 3-400 Mbyte each.
And all these raster are accessible by a remote shared server to our users.
For a total, actually, of about 13.000 rasters.

I don't understand if this new feature could be really usable in a
situation like our.

-- 
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Andrea Peri
. . . . . . . . .
qwerty àèìòù
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