XnView does'nt read properly Greyscale pictures

[floyer]

The Greyscale B&W pictures (8 bits) read by XnView are darker than those read by PhotoShop.
I tried to know why. My diagnosis is the following : XnView does'nt read properly Greyscale pictures.
Indeed, if I compare un greyscale chart read by PS and by XnView, I notice the following results :
read by PS / read by XnView
0 / 0
10 / 6
20 / 10
30 / 14
40 / 20
50 / 26
... / ...
100 / 65
... / ...
240 / 233
250 / 248
255 / 255

That explains the darkening !
The problem is the same with TIF or JPEG format

I located only one post about a similar problem but without solution to fix : http://newsgroup.xnview.com/viewtopic.php?f=36&t=25212

I'm using the last version (1.99.5) but the problem existed with the previous versions

Thanks a lot for your help

[floyer]

I forgot to mention that XnView is running under Windows XP SP3
Sorry

[MaxSt]

PhotoShop would sometimes apply color profiles...

You should try opening your images in other programs, to be sure.

[XnTriq]

• Willem van Schaik: PngSuite » Gamma values
• Henri Sivonen: The Sad Story of PNG Gamma “Correction”
• Trevor Morris: The PNG Gamma Dilemma

[floyer]

I've continued to investigate towards PS (thank to MaxSt for the idea!) and I noticed that the problem is only for the greyscale pictures resulted from a RGB to greyscale conversion done with PS. If the picture is originally a greyscale picture, PS and XnView read the picture in the same way!
Therefore, XNVIEW IS NOT RESPONSIBLE.
It's bother for me because I scan a lot of B&W negatives in RGB format and I convert in greyscale format with PS
(the conversion made by scanner is not satisfactory)
That means all my greyscale pictures converted with PS are not usable with other viewers.

Now, I must understand why PS applies such a profile when it converts, profile compensated when it reads the file.

Sorry to have you disturbed useless!

[floyer]

For those interested :
To avoid the above mentionned problem, you must modify the PS gray workspace : from "dot grain 15%" (default value) to "gray gamma 2.2"

[XnTriq]

For those interested :
To avoid the above mentionned problem, you must modify the PS gray workspace : from "dot grain 15%" (default value) to "gray gamma 2.2"

Thank you for reporting back, floyer (-:

FYI: Batch processing these samples…

• ew0031477633c-straightup-320-srgb.png
• ew0031477633c-black00.png
• ew0031477633c-black00-srgb1.png
• ew0031477633c-black07.png
• ew0031477633c-black07-srgb1.png

… with PngOptimizer gets rid of ICC profiles as well as gAMA chunks.

(Source files and output were inspected using TweakPNG.)