Ledsjovagen wrote:

 

When I use the quick selection tool to remove something, I am always left with a shadow counture of the area that I want to get rid of. I guess I have to make another kind of setting or something, but I cannot find any that works.

Photoshop CS6 W7

 

"left with a shadow counture of the area" The ares can have s sharp outlune or soft outline it should not have a shadow unless the layer has a layer style applied

Are you using Refine Edge after you select? You can shift the selection edge in or out in Refine Edge dialog.

Zoom in on the shirt edge. You'll see that the edge is soft/feathered - it fades from dark gray to light gray. Applying the Quick Select Tool to the shirt returns a feathered-edge selection, as you will see if you press Q to enter Quick Mask mode (press Q to exit Quick Mask, too). When you cut the selection, partially-selected pixels are left behind.

Instead of duplicating the original layer then selecting and cutting the background and shirt, use the Quick Select Tool to easily select the arm in the original layer (then click Refine Edge in the options bar and adjust the edge as desired) then press Ctrl+J to copy the arm alone to a new layer.

Ledsjovagen wrote:

 

Still this shadow is visible when I do some things with the picture, and I have not really found out exactly what makes this happen

The contour is a result of the selection having a feathered edge. The feathering is partial selection of pixels. When a partially-selected pixel is cut/deleted from a layer, the unselected proportion of the pixel will remain in the layer.

For example, you may have a pixel that's 75% selected. When cut from the layer, the pixel will not be completely removed. If the layer is Background, then the pixel will be mixed with the colour in the Background Color swatch. Other layers support transparency, so the pixel will retain its colour but its transparency will increase.