[cairo] How to brighten image, maintaining contrast?

[Stuart Axon]

Thanks, got this working using this in the end.
 
S++


>________________________________
> From: Bill Spitzak <spitzak at gmail.com>
>To: Stuart Axon <stuaxo2 at yahoo.com> 
>Cc: "cairo at cairographics.org" <cairo at cairographics.org> 
>Sent: Thursday, June 13, 2013 9:36 PM
>Subject: Re: [cairo] How to brighten image, maintaining contrast?
> 
>
>Try using the image itself as a source.
>
>Stuart Axon wrote:
>> I've been trying out some of the lighten some images, is there a way to 
>> brighten an image, but maintain contrast .. so far I've played LIGHTEN, 
>> HARD_LIGHT and SOFT_LIGHT - but images end up looking washed out.. any 
>> idea of a better approach ?
>>  
>> 
>> S++
>> 
>> 
>> Code is pretty simple at the moment;
>> 
>> 
>>         LIGHTEN_ALPHA = 0.25
>>         LIGHTEN_OPERATOR = cairo.constants.OPERATOR_LIGHTEN
>> 
>>         width = source_surface.get_width()
>>         height = source_surface.get_height()
>> 
>> 
>>         lightened = cairo.ImageSurface( cairo.constants.FORMAT_ARGB32, 
>> width, height )
>>         with cairo.Context( lightened ) as cr:
>>             cr.set_source_surface(source_surface)
>>             cr.paint()
>> 
>>             cr.set_operator( LIGHTEN_OPERATOR )
>>             cr.set_source_rgba(1, 1, 1, LIGHTEN_ALPHA)
>>             cr.paint()
>> 
>> 
>
>
>
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