jmoldata produces invalid pngs

Not invalid data. Post-PNG data is the Jmol state. In the case of PNGJ
output, it is the full structure and state in ZIP file format allowing the
PNG image to be dropped into Jmol to reproduce the full Jmol state at the
time the image was created and to record the state of Jmol at that time.
Note the early text field indicating 783 bytes of data starting at byte
88453. This allows Jmol to find the enhanced image data and process it.

000026: <02> <00> <00> <00> <00> <8D> \ <a7>
000034: <00> <00> <00> ! t E X t
000042: J m o l <20> T y p
000050: e <00> P N G 0 0 0
000058: 0 0 8 8 4 5 3 +
000066: 0 0 0 0 0 7 8 3
000074: 2 <a8> <dc> | # <00> <00> <00></dc></a8></a7>

Use

write "t.png" AS PNGJ

to request PNGJ format, which encapsulates all data necessary to reproduce
the image and state of Jmol.

On Thu, Feb 14, 2019 at 1:03 PM Yuri yurivict@users.sourceforge.net wrote:

---

• [bugs:#604] https://sourceforge.net/p/jmol/bugs/604/ jmoldata produces
  invalid pngs*

Status: open
Group: v14
Created: Thu Feb 14, 2019 07:03 PM UTC by Yuri
Last Updated: Thu Feb 14, 2019 07:03 PM UTC
Owner: nobody

I run plain scripts of the form

load '/tmp/pid8274-sno1.xyz';
write IMAGE 800 600 PNG '/tmp/pid8274-sno2.png';

with peptide molecules.

Produced pngs cause pngcheck to complain:

$ pngcheck ChemWiz-pid8274-sno2.png
ChemWiz-pid8274-sno2.png additional data after IEND chunk
ERROR: ChemWiz-pid8274-sno2.png

ffmpeg also complains about them:

[png @ 0x80cc19c00] Invalid PNG signature 0xA2F2A2A2A2A2A2A.
[concat @ 0x80cc4a000] DTS -230584300921369 < 1 out of order
DTS -230584300921369, next:80000 st:0 invalid dropping
PTS -230584300921369, next:80000 invalid dropping st:0
DTS -230584300921368, next:120000 st:0 invalid dropping
PTS -230584300921368, next:120000 invalid dropping st:0
[png @ 0x80ccf8000] Invalid PNG signature 0xA2F2A2A2A2A2A2A.
[png @ 0x80ccf9400] Invalid PNG signature 0xA2F2A2A2A2A2A2A.
DTS -230584300921369, next:80000 st:0 invalid dropping

The pngs are readable and do contain images, but it looks like they have
some invalid trailing bytes or something of this sort.

Jmol-14.29.31_1 on FreeBSD 11.2 amd64.

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--
Robert M. Hanson
Professor of Chemistry
St. Olaf College
Northfield, MN
http://www.stolaf.edu/people/hansonr

If nature does not answer first what we want,
it is better to take what answer we get.

-- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900

Ok, thanks for this explanation!
Please feel free to close it then.