When you want to create a stretch effect in Photoshop, there are a few things you need to know. First, you need to create a new layer on your canvas. Then, use the Pen tool to draw a line down the center of the layer. Next, use the Polygonal Lasso tool to select all of the pixels on the line and drag them towards the right edge of your canvas. Finally, use the Curl Tool to make them curl up towards the top edge of your canvas. This will create a stretched out effect.
