How to see detailed PNG properties?

[Karl Auer]

On Sat, 2022-09-17 at 15:18 +1000, Karl Auer wrote:
> I need to see *detailed* PNG image properties.

My apologies, I found the answer as soon as I'd posted. There is an
Ubuntu package called "pngtools" that includes the pngcheck program,
which generates output as below.

But now I need something that will strop those tEXT chunks out...

pngcheck -v stripped.png
File: ds_qr_with_mono_logo_300dpi_stripped.png (10744 bytes)
  chunk IHDR at offset 0x0000c, length 13
    300 x 300 image, 24-bit RGB, non-interlaced
  chunk gAMA at offset 0x00025, length 4: 0.45455
  chunk cHRM at offset 0x00035, length 32
    White x = 0.3127 y = 0.329,  Red x = 0.64 y = 0.33
    Green x = 0.3 y = 0.6,  Blue x = 0.15 y = 0.06
  chunk bKGD at offset 0x00061, length 6
    red = 0x00ff, green = 0x00ff, blue = 0x00ff
  chunk pHYs at offset 0x00073, length 9: 11811x11811 pixels/meter (300
dpi)
  chunk IDAT at offset 0x00088, length 10490
    zlib: deflated, 32K window, maximum compression
  chunk tEXt at offset 0x0298e, length 37, keyword: date:create
  chunk tEXt at offset 0x029bf, length 37, keyword: date:modify
  chunk IEND at offset 0x029f0, length 0
No errors detected in stripped.png (9 chunks, 96.0% compression).

Love the "pixels per meter" units! Like disk seeds in furlongs per fortnight :-)

Regards, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)
http://www.biplane.com.au/kauer