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inter_area interpolation method of resize

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V A
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inter_area interpolation method of resize

V A
Hello,

I send already a message for getting help about the OpenCV function resize. Could you allow please the post of this message in the group?
Thank you.

I have a question about the function resize, specifically the input parameter interpolation:
void resize(InputArray src, OutputArray dst, Size dsize, double fx=0, double fy=0, int interpolation=INTER_LINEAR ) 


When setting interpolarion = INTER_AREA, whose definition is: "INTER_AREA - resampling using pixel area relation. It may be a preferred method for image decimation, as it gives moire’-free results. But when the image is zoomed, it is similar to the INTER_NEAREST method."

Could anyone help me giving me some details about the "pixel area relation" interpolation method?
 
Thank you very much,
Patricia
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Re: inter_area interpolation method of resize

Shervin Emami
If I remember correctly:

INTER_NEAREST is the fastest method and creates blocky images by just
choosing 1 pixel to replace several pixels.
INTER_AREA is a fast method that gets the average of several pixels, which
is good for shrinking an image but not so good for enlarging an image.
INTER_LINEAR uses bilinear interpolation to resize the image by combining
several pixels nicely (the best choice in many situations).
INTER_CUBIC uses bicubic interpolation to use more advanced resizing that
linear, so is slightly slower but looks slightly better sometimes and
slightly worse other times.

Cheers,
Shervin Emami.
Mobile Computer Vision Engineer, NVIDIA.
http://www.shervinemami.info/openCV.html


On Wed, Jan 11, 2012 at 2:27 PM, V A <[hidden email]> wrote:

> **
>
>
> Hello,
>
> I send already a message for getting help about the OpenCV function
> resize. Could you allow please the post of this message in the group?
> Thank you.
>
> I have a question about the function resize, specifically the input
> parameter interpolation:
> void resize(InputArray *src*, OutputArray *dst*, Size *dsize*, double *fx*=0,
> double *fy*=0, int *interpolation*=INTER_LINEAR )
>
> When setting interpolarion = INTER_AREA, whose definition is: "*INTER_AREA
> * - resampling using pixel area relation. It may be a preferred method
> for image decimation, as it gives moire’-free results. But when the image
> is zoomed, it is similar to the INTER_NEAREST method."
>
> Could anyone help me giving me some details about the "pixel area
> relation" interpolation method?
>
> Thank you very much,
> Patricia
>
>  
>
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Re: inter_area interpolation method of resize

o0o0o
This post has NOT been accepted by the mailing list yet.
Hello,

I can not find any paper which tell the details of INTER_AREA. But now, I want to realize it on GPU.
Could you please help me to get some mathmatical expressions of how to caculate INTER_AREA method of resampling an image.

Thank you!


 
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