very strong contrast enhancement

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very strong contrast enhancement

Michael Koch
Which is the recommended filter for a very strong contrast enhancement,
up to a factor of 10?

The eq=contrast=... filter allows only a maximum of 2. Could this be
changed to allow higher values?
As a workaround I'm using 3 or 4 cascaded eq filters.

I did also try  geq=r='5*r(X,Y)':g='5*g(X,Y)':b='5*b(X,Y)'
but this filter is slow and it seems there is no limiter when an
overflow occurs.

Are there any other filters for strong contrast enhancement?

Thanks,
Michael

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Re: very strong contrast enhancement

Paul B Mahol
On 2/25/19, Michael Koch <[hidden email]> wrote:
> Which is the recommended filter for a very strong contrast enhancement,
> up to a factor of 10?
>
> The eq=contrast=... filter allows only a maximum of 2. Could this be
> changed to allow higher values?
> As a workaround I'm using 3 or 4 cascaded eq filters.

Is your source RGB or YUV?
There are missing filters for gamma/saturation/hue/contrast in RGB.

>
> I did also try  geq=r='5*r(X,Y)':g='5*g(X,Y)':b='5*b(X,Y)'
> but this filter is slow and it seems there is no limiter when an
> overflow occurs.
>
> Are there any other filters for strong contrast enhancement?
>
> Thanks,
> Michael
>
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Re: very strong contrast enhancement

Michael Koch
Am 25.02.2019 um 15:58 schrieb Paul B Mahol:
> On 2/25/19, Michael Koch <[hidden email]> wrote:
>> Which is the recommended filter for a very strong contrast enhancement,
>> up to a factor of 10?
>>
>> The eq=contrast=... filter allows only a maximum of 2. Could this be
>> changed to allow higher values?
>> As a workaround I'm using 3 or 4 cascaded eq filters.
> Is your source RGB or YUV?
> There are missing filters for gamma/saturation/hue/contrast in RGB.

yuv422p10le

Michael


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Re: very strong contrast enhancement

Michael Koch
In reply to this post by Michael Koch
Am 25.02.2019 um 15:34 schrieb Michael Koch:
> Which is the recommended filter for a very strong contrast
> enhancement, up to a factor of 10?
>
> The eq=contrast=... filter allows only a maximum of 2. Could this be
> changed to allow higher values?
> As a workaround I'm using 3 or 4 cascaded eq filters.

Another possible workaround for strong contrast enhancement is the
curves filter, but it's slower than three cascaded eq filters, and it's
not linear because it uses a smooth curve through the points:
curves=all='0/0 0.125/1 1/1'

It would be nice if the curves filter had a "linear" option instead of
the smooth curves.

Michael

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