You will need
  • - Photoshop
  • - processing (image) for the new background
Download the software Photoshop. In it, open a picture: File - Open. Copy the layer: in the layers tab, click the right mouse button and select "Duplicate layer" (Duplicate layer). Further work on the duplicate.
Well, when the background is almost monochrome, and the object contrast greatly with him. In this case, to remove the background is easy. Select the tool "Magic wand" (Magic Wand) and click on it. Maybe once the whole background will not stand out. So continue to press in his region a "Magic wand", hold down the Shift key. When everything is highlighted, click the Delete key (after turning off the layer visibility of the Background layer). So the area around the object will become transparent.
If the object and its environment is not strongly contrasted and have the same shades, it may be difficult to quickly select the background. Use the Eraser tool (Eraser) - it draws the backgroundish color, if the image has one layer, and transparent if the two layers. Walk them around the object. It is good when you want to remove complex or small parts of the image. Use it in brush mode, which will set the appropriate parameters (opacity, diameter, etc.).
It often happens that the boundary object around which removed the background, it contains particles and is somewhat rough and sloppy. You can compensate if it's a little blur. Click "Selection" (Selection) - Convert (Modify) - "Border" (Border). Set the border width in the range of a few pixels, e.g., five (see op's situation). Go to the tab "Filter" (Philtre) - "Blur" (Blur) - "Gaussian blur" (Gaussian Blur), set radius to somewhere less than one, that the boundary was not sharp. Clear the selection.
Open a pre-prepared background, for example, a picture of a beach or other picturesque place. Drag in the current document. She will move into it as a new layer. Place it under the layer with the object, e.g., person. Now the man was on a new background. Press "edit" (Edit) - "Free transform" (Free transform) and hold down the Shift key, place the new backgroundlayer new successful way. Press Enter to apply the changes.
If object boundaries are not always clear and contain, for example, traces of the old backgroundand use the "Eraser" (Eraser), "burn" (Burn Tool) and "Dodge" (Dodge Tool), depending on the situation. The goal is to make the object successfully combined with the new backgroundohms.
At the end connect the layers into one single layer: Layers - Merge layers.