Nicu's How-to - Turn a digital photo into Polaroid with GIMP

Introduction

There are other tutorials where I covered various techniques of photo enhancement and manipulation, but there are times when you want more bling, something that makes a photo really stand out and such a cool looking trick is the Polaroid effect which we will explore step by step, trying to learn some more things about GIMP in the process.
As usual, there are no hard rules and we are free to experiment with shapes, positions and parameters, skip optional steps and try alternate ways and the result may vary according with those alterations:

The Polaroid effect

The first step is to open the photo in GIMP and add an Alpha Channel (JPEG files don't have an alpha channel) as we will work with transparency (Layer > Transparency > Add Alpha Channel):

Now enlarge the image (the canvas), to make room for the Polaroid border (Image > Canvas Size). Move (drag & drop) the active photo somewhere in the middle of the enlarged canvas:

Add a new layer (Layer > New Layer) and move it (drag & drop) under the photo layer, we will use it to hold the paper border:

Use the Rectangle Select Tool to make a rectangular selection in the new layer around the photo, it will be the border. For a realistic Polaroid, make the bottom border thicker:

We can fill the selected rectangle with white, as it is paper, or with a very light grey, to get a bit of contrast if we put the photo over a white background. My preference was to select a very light grey as foreground color and fill the rectangle with a gradient from light grey to white:

The result is like this, it starts to resemble a photo:

For increased realism, add a small drop shadow (Filters > Light and Shadow > Drop Shadow). Select some values as you like, I used some small values:

Now the photo has a slight 3D look:

Use the text tool, select a nice hand font (we want a realistic effect, remember) and write something:

To get a clearer view, add a new layer, fill it with white and move it at the bottom (under the drop shadow):

Now merge down the text layer and the photo with the paper layer, we need them in one piece for the next step (bending):

This is how it should look:

Now We will bend the photo a little. I am not entirely happy about how GIMP deals with the effect, the result is not antialiased enough, so at the end I present an alternate way to get the effect using another filter, IWarp.
So use the Curve Bend filter (Filters > Distorts > Curve Bend), make sure Smoothing and Antialiasing are checked, check Live Preview too if you want, and play with the upper and lower Curve for Border. You can make them identical (copy) or slightly different, depending on what bend you want:

We will get something like this, the paper is a bit displaced from the shadow, but we will deal with that in the next step:

Move the photo layer to fit the shadow and then merge them together:

Use the Rotate Tool and rotate the photo layer a bit for even more realism:

We are almost done, we can stop here if we want, but there is more:

Now we will add a piece of adhesive tape to keep the photo "glued". So start by creating a new transparent layer on top.

On this emply layer make a rectangular selection and fill it with some color (depending on what type of adhesive tape you like):

Use the Eraser Tool and make the tape ends look realistic:

Select the tape (a rectangular selection around it), rotate it and move in the desired position (a corner or a margin):

For a relief look, add a slight drop shadow to the tape (I used smaller values compared with the ones used for the paper's shadow):

Merge the tape layer with its shadow and decrease the opacity if you want a transparent tape:

And this time we really are done:

We can leave the background solid or remove it and have transparency:

Or fill the background with a texture (I used here a cork board texture):

As I said above, I am not very happy with the results of the Curve Bend effect in GIMP, so we can use another filter instead, IWarp (Filters > Distorts > IWarp).