Interfaces: PC and MAC and the screenGamma property...

[Dar Scott]

On Friday, January 2, 2004, at 06:10 PM, Dar Scott wrote:

> text
> Length: 879
> 89504e470d0a1a0a0000000d4948445200000050000000500802000000017365
> fa
> 00000004
> 67414d41   <-- gAMA
> 0000afc8   <-- value

Gamma = 2.222222

> 37058ae9
> 0000001974455874536f6674776172
> 650041646f626520496d616765526561647971c9653c000003014944415478da
...


> export PNG
> Length: 261
> 89504e470d0a1a0a0000000d4948445200000050000000500803000000b9cf02
> 9f
> 00000004
> 67414d41  <-- gAMA
> 0000e5c83  <-- value

whoops

000e5c8 <--- value

Gamma = 1.699986


> d932d66

whoops 3d932d66
> 0000002d504c54456868687979798b
> 8b8b7070708282829d9d9db0b0b0edededd9d9d9f7f7f7e3e3e3ffffffcfcfcf
...

It looks to me that the PNG you have is basically a 2.2.  The export 
converts it to a 1.7.

Both imageData and the P6 export show pixels as 86,86,86 hex.

However, the JPEG shows up as 80,80,80 in imageData and in the P6 
export.

I wonder if the 86 hex is an attempt to lighten up the image by 
Revolution.

Is 134 at 1.7 Gamma the same as 128 at 2.2 Gamma?

Dar Scott