How to bring back the arched image in jpeg to straight flat art

[Kie22297069ae07]

Hi! I have to create a flat art (straight rectangle shape) from a given jpeg illustration. The illustration is applied arched effect and saved as jpeg. How do I bring back to the straight flat art form in illustrator??

- I tried to apply arch effect to the opposite direction to straighten it. But the shape get stretched and did not work... 

If you know how to do it, please help!

Thank you!

[Anna Lander · Accepted solution]

Sorry, no way. JPG format is raster, it's different from the vector objects which you can distort more or less safely. Any new distortions will make the image just worse.
If the original rectangle was filled with a gradient, try to get the main colors, create a new rectangle and fill it with this gradient. If it's a pattern, try to redraw the pattern element, create a new pattern and fill the rectangle. If there is a photo or another complex image, you have no way to restore it but to redraw it from scratch.  

[Kie22297069ae07]

Hello Anna! Thank you for your response. It is very helpful information!