[FFmpeg-devel] [PATCH] Add a gamma flag to exr loader to avoid banding

[Gonzalo Garramuno]

On 28/04/14 20:21, Gonzalo Garramuno wrote:
> On 28/04/14 17:10, Michael Niedermayer wrote:
>> On Mon, Apr 28, 2014 at 09:19:07PM +0200, Reimar Döffinger wrote:
>>
>>>> patience
> I apologize for being so impatient.  Sorry.
>>>> First it seems to still have a bug
>>>> it fails fate
>>>> --- ./tests/ref/fate/exr-slice-raw      2014-04-28 
>>>> 04:14:37.849375679 +0200
>>>> +++ tests/data/fate/exr-slice-raw       2014-04-28 
>>>> 19:50:27.430558597 +0200
>>>> @@ -1,2 +1,2 @@
>>>> #tb 0: 1/25
>>>> -0,          0,          0,        1,  3169800, 0x6a356d0d
>>>> +0,          0,          0,        1,  3169800, 0x2cfefd25
> I am stuck with this bug.  Not sure exactly what the numbers mean in 
> the first place, except that it seems +0 and -0 are misplaced.
I have a new update to fix the bugs in the code but it still does not 
pass fate.

  #tb 0: 1/25
-0,          0,          0,        1,  3169800, 0x6a356d0d
+0,          0,          0,        1,  3169800, 0x1f656d7a

My feeling is that it will never pass it, since float->half is a lossy 
operation, so exr_flt2uint() returns a different float value than 
exr_half2float() which is a lossless operation.

I am checking with the OpenEXR guys to make sure my assumption is 
correct.  If it is, I'll post a new update and an updated fate checksum.