Transforming a photo into sketch
Transforming a photo into a pencil sketch can be a very useful and artistic effect. The result image can be used in any kind of interface, or to produce a stylistic avatar. Some people have even used it to produce beautiful images to print and add to photo albums.
Here you will learn how to use correctly the "Sketch" effect of "Photo Effects" section, so you will able to get good quality sketches from photos.
For this tutorial we will use the photo showed below. It's not good to turn into sketch because it's very dark mainly in its bottom, and that's the reason we will use it. Let's try to get a good result from a bad initial photo.
First of all, be sure you are looking for a pencil sketch effect. If a black pencil drawing effect is better for your needs, so don't use the sketch effect. You can transform photos into pencil drawings using Picture to People and the results are very different from the sketch ones. Below you see two different effects to transform a photo into a pencil drawing.
Using the effects in [Photo Effects] / [Pencil] you can get the results above. In this case, I used the first and second pencil drawing effects respectively.
If the images above are not the kind of result you are looking for, so let's try the sketch effect, what generates a stronger "draft" appearence. In this tutorial, we will always use the first sketch effect (there are three), because it has small and more detailed strokes, but the explanations can be used for the other two effects too.
First we will modify the photo turning it gray. Go to [Image Editor] / [Grayscale] and apply the first transformation to get something like this.
Now go to [Photo Effects] / [Sketch] and apply the first effect. You will get this result.
The result is not good. Almost all information was lost. This illustrates a very important feature of this effect, and you should know it to get good results. To be really generic, the generator of this effect must be very sensible to any darkness. It means the used image was too dark to be a good input, because it causes most of output image to be strongly drawn.
Now we will try to solve this problem with very simple pre-processing. Go to [Image Editor] / [Brightness] and improve the brightness of the gray photo in 40%. You will get this image.
Applying again the sketch effect, you get the image showed below. As you can see, with a more bright input you get a better output. It's possible to see the more important photo regions in this output image.
With another simple pre-processing we can get a result with a better separation between the blank parts and the drawn regions. Go to [Image Editor] / [Contrast] and improve the contrast of the last input image in 40%, so you will get this.
Applying the sketch effect, you get this final result. It's a nice sketch of a clown.
I have shown you how the brightness, darkness and contrast of a photo can affect the result of the sketch effect. You can create your own ways to pre-process your photos to get the best results. If you give a really good input to the effect generator, you will get a very well drawn and clear sketch.