Doesn't the fact that everything interesting ends up in out-0.png tell us that the alpha was black all along, and it was the red channel that you're after?
> On Feb 8, 2019, at 2:03 PM, Stephen Parker <[email protected]> wrote: > > ... actually, disregard the -swap as -separate is all that's needed. > > convert test.png -separate out.png > > On Fri, Feb 8, 2019 at 1:51 PM Stephen Parker <[email protected] > <mailto:[email protected]>> wrote: > 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] > <mailto:[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] >> <mailto:[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] >>> <mailto:[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] >>> <mailto:[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] >>>> <mailto:[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] <mailto:[email protected]> >>>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>>> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >>> >>> -- >>> Larry Gritz >>> [email protected] <mailto:[email protected]> >>> >>> >>> >>> >>> _______________________________________________ >>> Oiio-dev mailing list >>> [email protected] <mailto:[email protected]> >>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >>> <test.png>_______________________________________________ >>> Oiio-dev mailing list >>> [email protected] <mailto:[email protected]> >>> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >>> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> >> >> -- >> Larry Gritz >> [email protected] <mailto:[email protected]> >> >> >> >> >> _______________________________________________ >> Oiio-dev mailing list >> [email protected] <mailto:[email protected]> >> http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org >> <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> > > -- > Larry Gritz > [email protected] <mailto:[email protected]> > > > > > _______________________________________________ > Oiio-dev mailing list > [email protected] <mailto:[email protected]> > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org > <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> > _______________________________________________ > Oiio-dev mailing list > [email protected] > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org -- Larry Gritz [email protected]
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