The VXL Project

Szabolcs Berecz wrote about converting a greyscale image to
vil_image_view<vil_rgb<vxl_byte> > and saving it:
> The problem is, I can't save images converted with this function. With
> png format I get the error message:
> 
> ERROR! vil_png_file_format::make_output_image()
> Pixel format should be byte, but is vil_rgb<vxl_byte> instead.
> vil_new: Cannot new to type [png]

The problem is that vil generally prefers to treat images as
multi-planar, so that a 3-component RGB image is regarded as a 3-plane
image with a planestep of 1 (i.e. interleaved planes). If you have
your rgb image from your function and write
   vil_image_view<vxl_byte> rgb_planes = rgb;
you'd get an image such that
   rgb_planes(i,j,0) == rgb(i,j).r  &&
   rgb_planes(i,j,1) == rgb(i,j).g  &&
   rgb_planes(i,j,2) == rgb(i,j).b

(This won't actually copy data, so you don't have to worry about
efficiency.) You should be able to save this planar image.

Amitha.

On 3/6/06, Amitha Perera <perera@...> wrote:
> The problem is that vil generally prefers to treat images as
> multi-planar, so that a 3-component RGB image is regarded as a 3-plane
> image with a planestep of 1 (i.e. interleaved planes). If you have
> your rgb image from your function and write
>    vil_image_view<vxl_byte> rgb_planes =3D rgb;
> you'd get an image such that
>    rgb_planes(i,j,0) =3D=3D rgb(i,j).r  &&
>    rgb_planes(i,j,1) =3D=3D rgb(i,j).g  &&
>    rgb_planes(i,j,2) =3D=3D rgb(i,j).b
>
> (This won't actually copy data, so you don't have to worry about
> efficiency.) You should be able to save this planar image.
>
> Amitha.
>

Thanks for the explanation!

Szabi

Whilst Amitha is correct, there is a general fix to VXL for this 
problem, which I thought I had committed about a month ago. It is 
committed now, and there is a copy of the patch in the attached email.

Ian.

Amitha Perera wrote:
> Szabolcs Berecz wrote about converting a greyscale image to
> vil_image_view<vil_rgb<vxl_byte> > and saving it:
> 
>>The problem is, I can't save images converted with this function. With
>>png format I get the error message:
>>
>>ERROR! vil_png_file_format::make_output_image()
>>Pixel format should be byte, but is vil_rgb<vxl_byte> instead.
>>vil_new: Cannot new to type [png]
> 
> 
> The problem is that vil generally prefers to treat images as
> multi-planar, so that a 3-component RGB image is regarded as a 3-plane
> image with a planestep of 1 (i.e. interleaved planes). If you have
> your rgb image from your function and write
>    vil_image_view<vxl_byte> rgb_planes = rgb;
> you'd get an image such that
>    rgb_planes(i,j,0) == rgb(i,j).r  &&
>    rgb_planes(i,j,1) == rgb(i,j).g  &&
>    rgb_planes(i,j,2) == rgb(i,j).b
> 
> (This won't actually copy data, so you don't have to worry about
> efficiency.) You should be able to save this planar image.
> 
> Amitha.
> 
> 
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