Legacy ImageMagick Discussions Archive

There was a problem with timezones east of GMT zone. I was using an unsigned int for "addhours"
but it can be negative. Working on a fix.

Could you post your two PNG output files somewhere that we can retrieve them
or if you prefer, run "pngcheck -v file.png" on both and post the result here?

This does not seem to work with a PNG image that contains a tEXt chunk with copright. The copyright line does show up in the output of identify -verbose as a Copyright property. Properties: Copyright: � 2013,2015 John Cunningham Bowler date:create: 2017-08-14T17:12:35-04:00 but does not show up in t...

It was a temporary glitch, due to some timestamps having the offset from UTC recorded as "Z" instead of "[+-]hh:mm", in IM-7.0.6-6 and 6.9.9-6.

Fixed. I added "addhours" and "addminutes" to the scan of "date", and added
that to the existing hours and minutes. Needs more work to handle February
28 on leap years, though.

coders/png.c, line 8178, write_tIME_chunk(), gets the time from time_t ttime; time(&ttime); On my Ubuntu platform, "man 2 time" claims that it returns time in UTC. However, I confirm that a PNG image created at 19:54 EDT gets a tIME chunk with 19:54 UTC. The date:create property comes ...

This is a followup to a complaint on the Kudos and Rants Forum. IM7 is too verbose when it can't find a file, as in magick nothing.jpg output.png Im6 only emits 2 lines while im7 seems to get into "property.c" with invalid input, and emits about 3 more error messages. Also, "magick co...

In the related bug report I've fixed coders/png.c so that pixels survive multiple round trips between HDR and PNG formats.

I've pushed a change to the IM7 git repo The "one" demo works nicely; the pixel values survive the round-trip PNG->HDR->PNG->HDR: one: 0,0: (65535,32896,0) #FFFF80800000 srgb(255,128,0) one.hdr: 0,0: (65535,32768,0) #FFFF80000000 rgb(100%,50%,0%) one.hdr.png: 0,0: (65535,32896,0) #FF8000 r...

The png reader is setting gamma to1.0 but neglects to reset the image colorspace. That would be a bug that needs to be fixed.
I'm testing a patch now.

Am I missing something? Wasn't there an issue about IM not doing a round trip correctly? Not reading linear PNG files correctly? Has that been resolved, or is someone investigating? It's still open as far as I am concerned. Incidentally, the one.hdr.png file from my demo does happen to be 16-bit (4...

There's no harm in writing 16-bit sRGB PNG images.

... And they recommend exporting images as 8-bit sRGB for use by the world, ... Okay, so, at least if we're writing an 8-bit per sample PNG file would you agree that sRGB should be the default, rather than whatever-colorspace-the-image-just-so-happens-to-already-be-in-for-whatever-reasons? The libp...

Right, "random-threshold" reduces the image to black and white pixels. I think there's a way to random-dither each channel to get an 8-color image. But no way to get a 256-color image with it.

Use -sample instead of -resize if you don't want to add interpolated colors.