#586 Identify returning wrong compression values

[Mikko Ala-Fossi]

When identifying jpeg images you get normal, expected results.

Executing with -format identity does not return correct jpg compression values.
gm identify -format '%f: %Q\n' *

new2.jpg: 75
photo.jpg: 75
profimg.JPG: 75

The expected results can be found with the ImageMagick tool
identify -format '%f: %Q\n' *

new2.jpg: 90
photo.jpg: 98
profimg.JPG: 60

Version used:
GraphicsMagick 1.4 snapshot-20180922 Q16 http://www.GraphicsMagick.org/

[Bob Friesenhahn]

Executing with -format identity does not return correct jpg compression values.
gm identify -format '%f: %Q\n' *
```
new2.jpg: 75
photo.jpg: 75
profimg.JPG: 75

This is a new problem added in the latest release. I changed the JPEG
reader 'ping' operation to quit sooner than it did before due to a
denial of service (DOS) opportunity.

If you add the +ping option, then the results will be as before, but
this causes the image pixels to be read.

Bob

[Bob Friesenhahn]

This problem is fixed by Mercurial changeset 15873:8b84cdc9f9cd. Thanks for reporting this issue.