How to stretch pixels across a page

Thank you all for your response. Some of those solutions may just work.

In case you are interested what I am actually trying to achieve. I want to add roads lakes and buildings to satellite height maps. Because none of those "flat" features are seen in height maps. So my plan was to make a mask of those flat features and apply it to the heightmap. The tricky part is to keep these flat features following the contours of the land.

It's not that easy to do with a curved selection, because distorting that would distort the curve itself rather than smearing out the pixels. However, I don't think the result would be much different from a straight one pixel vertical selection, providing that you place that selection carefully, just right of her eye.

This turns out to be not that straight forward, and my first two attempts failed completely.  So what I had to do is create a line through the most interesting colours using Quick Mask

Turn off Quick Mask and copy the selection to a new layer

Make a bunch of copies, and distribute using the align tools

Merge those layers.

Repeat and copy again

Continue the process until you fill the page

Then decide what you want to do.

Motion Blur will iron out the lumps and bumps

Polar Coordinates — it does not fill the layer so you need to copy and rotate

Glowing Edges (wot larks we is hav'n)

Star Filter Pro 4

What time is it?  I think we have time for a few more ;-)

Some texture

Oil Paint  — there's a law against leaving it out.

A nice button.  You could eat this

We call this effect Ged

If I can understand correctly what you really want then do the following:

• Use Pen Tool with Path drawing mode to create curved line and along the way outline left or right side of the image. One side should be curved line and other three sides should be straight lines.
• Create selection from path then use selection to create layer mask. If you want you can expand or contract selection along the way.
• Duplicate layer and invert layer mask as needed. Apply layer mask to cut (crop) the image with curved line then do whatever you want to do.

Hopefully this will help you or at least give you idea how to.