Resize a portion of an image or Curved Resize

[coolperez8]

So, let's say I have an image. There are three scenarios I want to try. Let's say the image is 3000 pixels in either width or height, I want to try these scenarios affecting either, but not both. The scenarios assume I am editing the height:

First, I want to try cropping the image and only resizing the bottom 500 pixels to double the size, but leaving the rest of the image unaffected.

Next, I want to try a "curved resize", basically scanning the entire image from top to bottom and resizing each Y co-ordinate individually by an increasing interger, so the top of the image would not be resized but the bottom of the image would be multiplied by 3.

Lastly, I want to try the same curved resize, but instead it would resize the entire bottom 500 pixels by 3 rather than just the last row. In other words, it's basically doing the curved resize mentioned before from 1-2500, but when it hits 2500 it resizes 2500-3000 by 3.

[snibgo]

Let's use an image with a grid, for clarity.

First, I want to try cropping the image and only resizing the bottom 500 pixels to double the size, but leaving the rest of the image unaffected.

You seem to want a simple chop and resize. Windows BAT syntax:

Code: Select all

%IM%convert ^
  %SRC% ^
  -gravity south ^
  ( -clone 0 -chop 0x50 ) ^
  ( -clone 0 -crop x50+0+0 +repage -resize "100x200%%^!" ) ^
  -delete 0 ^
  -append ^
  vary_scale_c.png

Next, I want to try a "curved resize", basically scanning the entire image from top to bottom and resizing each Y co-ordinate individually by an increasing interger, so the top of the image would not be resized but the bottom of the image would be multiplied by 3.

I think you want a variable scale in the y-direction: varying the scale between 1.0 at the top and 3.0 at the bottom.

Code: Select all

set IDENT=^
0,0,#008,^
%%[fx:w-1],0,#f08,^
0,%%[fx:h-1],#0f8,^
%%[fx:w-1],%%[fx:h-1],#ff8

%IM%convert ^
  %SRC% ^
  -resize 100x150%% ^
  ( +clone ^
    -sparse-color bilinear "%IDENT%" ^
    -channel G ^
    -function Polynomial -0.5,1.5,0 ^
    +channel ^
  ) ^
  -compose Distort -set option:compose:args 100%%x100%% -composite ^
  vary_scale_vs.png

Lastly, I want ...

Combine the above two methods.

EDIT: Dodgy maths corrected (I hope).

[coolperez8]

Let's use an image with a grid, for clarity.

First, I want to try cropping the image and only resizing the bottom 500 pixels to double the size, but leaving the rest of the image unaffected.

You seem to want a simple chop and resize. Windows BAT syntax:

Code: Select all

%IM%convert ^
  %SRC% ^
  -gravity south ^
  ( -clone 0 -chop 0x50 ) ^
  ( -clone 0 -crop x50+0+0 +repage -resize "100x200%%^!" ) ^
  -delete 0 ^
  -append ^
  vary_scale_c.png

Next, I want to try a "curved resize", basically scanning the entire image from top to bottom and resizing each Y co-ordinate individually by an increasing interger, so the top of the image would not be resized but the bottom of the image would be multiplied by 3.

I think you want a variable scale in the y-direction: varying the scale between 1.0 at the top and 3.0 at the bottom.

Code: Select all

set IDENT=^
0,0,#008,^
%%[fx:w-1],0,#f08,^
0,%%[fx:h-1],#0f8,^
%%[fx:w-1],%%[fx:h-1],#ff8

%IM%convert ^
  %SRC% ^
  -resize 100x150%% ^
  ( +clone ^
    -sparse-color bilinear "%IDENT%" ^
    -channel G ^
    -function Polynomial -0.5,1.5,0 ^
    +channel ^
  ) ^
  -compose Distort -set option:compose:args 100%%x100%% -composite ^
  vary_scale_vs.png

Lastly, I want ...

Combine the above two methods.

EDIT: Dodgy maths corrected (I hope).

Ok, thanks