Re: [Gimp-user] About the function `Brighten in 'Lens distortion filter'

["David Gowers (kampu)" <00ai99 gmail com>]

On Sat, Feb 4, 2012 at 8:16 PM, Minniu Zhou <minniu2003 yahoo com> wrote:

About the function `Brighten in 'Lens distortion filter'

 

Hi, I am Syu, I have a question and hope if some kind peoples can help me to find the answer,

it will be very helpful for me.

I am not good at English, hope you will try to understand my problem. I will try my best to write...

I am a lecturer and I want to introduce the Gimp to my students here in Japan, using to make image processiong. 

I think it is a wonderful tool and thanks all for make it possible to be free ! 

 

Well, I have a question about the filter namede'Lens distortion',  especially the funtion of 'Brighten'.

It is explained as ''The 'Main' or 'Edge' options must be non zero for this option to produce noticeable result."

Why? If I don't want to change the shape of the image, what should I do ?

Hi Syu,
 

This function, as I understand it, is intended to correct an error of some cameras, where towards the edges of the picture -- the same areas that tend to suffer from lens distortion --, the colors are darkened. That is why the function only operates in the areas where you have specified there is distortion.

If you simply wish to brighten the image, I suggest "Brightness-Contrast", found in the Colors menu.

I hope that helps.

David