Try: convert test.png -separate -swap 4,0 out.png
You should get an image written out for each channel. "out-0.png" can be opened in Preview.app. -s On Fri, Feb 8, 2019 at 1:38 PM Larry Gritz <[email protected]> wrote: > On my mac, ImageMagick "convert test.png test.tif" also results in what > appears to be a black image. > > And using ImageMagick's "identify -verbose", I see these stats: > > Alpha: > min: 0 (0) > max: 0 (0) > mean: 0 (0) > standard deviation: 0 (0) > kurtosis: -3 > skewness: 0 > entropy: 0 > > Are you *sure* that the alpha channel isn't really 0 everywhere? > > > > On Feb 8, 2019, at 11:55 AM, Larry Gritz <[email protected]> wrote: > > Hmmm... it's not just "--ch", that image looks "black" (all 0.0 values) in > all channels to all OIIO tools. (For example, `oiiotool -stats test.png`) > I'm suspecting something in the reader rather than an issue with channel > selection. > > Looking into it. > > -- lg > > > On Feb 8, 2019, at 11:31 AM, Stephen Parker <[email protected]> > wrote: > > Hi Larry, > > I'm on the release branch. Here is the PNG in question (attached). > > thanks > > On Fri, Feb 8, 2019 at 11:12 AM Larry Gritz <[email protected]> wrote: > >> Which version of OIIO? >> And I don't suppose you can send me an example PNG that has the problem? >> Or is it weird for every png you try? >> >> >> >> On Feb 8, 2019, at 10:59 AM, Stephen Parker <[email protected]> >> wrote: >> >> Hello, >> >> I'm having some trouble using oiiotool's copy channel operator. It might >> be user error but I wanted to check and see if it's intended behavior. I've >> only glanced at the code so far. >> >> My test image is a PNG (4-channel RGBA), but only has information in the >> Alpha. When attempting to copy the Alpha into the other 3 channels and >> write out an RGB image (no Alpha), I get black. Imagemagick's 'convert' did >> what I expected. >> >> invoked as: >> >> oiiotool input.png --ch "R=A,G=A,B=A" -o output.png >> >> I also tried using the numeric channel labels to no avail. >> >> -sp >> _______________________________________________ >> Oiio-dev mailing list >> [email protected] >> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >> >> >> -- >> Larry Gritz >> [email protected] >> >> >> >> >> _______________________________________________ >> Oiio-dev mailing list >> [email protected] >> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >> > <test.png>_______________________________________________ > Oiio-dev mailing list > [email protected] > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org > > > -- > Larry Gritz > [email protected] > > > > > _______________________________________________ > Oiio-dev mailing list > [email protected] > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org > > > -- > Larry Gritz > [email protected] > > > > > _______________________________________________ > Oiio-dev mailing list > [email protected] > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >
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