Graphic novel progress - Colour vectorising a pencil sketch

After three weeks of working away (in between other bits and bobs), I've made some progress on the graphic novel. The first week or so was spent investigating whether I could do the work in gouache - a sort of paint similar to watercolour but less watery (I know that's not a very technical or accurate description but it'll do). I've done gouache illustrations before, I've popped one alongside this text.

I found though that it is a slow job doing the gouache. I think I'd need to spend six months or probably longer just practicing the gouache to get good enough to churn out an entire page of gouache illustration in one day (my target rate). Juanjo Guarnido - the Blacksad artist - has certainly found a way to produce his painted artwork at a viable rate but he's spent years doing fine art followed by more years working as a Disney animator. That's a lot of practice!

I've therefore switched to plan B; draw pencil sketches, ink them, scan the black and white inked pages, fill the areas with colour on the computer, add some shading and lay them out. Voila!, one graphic novel page. Here's how I did it:

First off, I draw a pencil sketch.

There's no shading in this pencil sketch, that'll be added later. I've also got to remember not to do too fine detail in the picture. Very fine details will be lost during the later stages of the process.

The next step is to make a line drawing of the picture. In the past, I've draw the black lines on with technical pens of various thicknesses (0.1 to 0.5) and then rubbed out the pencil lines. This though is a grubby process and often leaves smudges and fragments of pencil lines in the final inked version. Instead, I'm now using a light-box that my dad made several years. I put the pencil sketch over the light-box, put a new sheet over that and trace the ink lines on a new, fresh sheet. That way, the new sheet has only ink lines and is as clean as clean can be.

I then scan the inked version into the computer. Because it's only black lines, I can choose to scan it as a black and white image at a high resolution (600dpi) without my computer keeling over (that's because each pixel is only 1 or 0 - black or white, rather than each pixel being one of 2,000 possible colours, making the file size much smaller).

Now comes the tricky bit. I've got a very clean and attractive line drawing of my picture but I want to turn it into a colour picture. My plan is to add colours to areas of the picture, a bit like colouring by numbers. A graphic comic painted in this way is known as 'ligne claire' or 'clear line'. Possibly the most famous example of this is Tintin, shown below.

Notice that all the colours in the picture are flat, matt colours. You'd think that having flat areas of colour would be dull but it seems that if you do the line work well, the eye doesn't mind. I think the 'clear line' approach is very attractive (I've always been a big fan of Tintin). Not only that, but it's potentially faster than fully painted pictures. What I'm most interested in at the moment though is to take the flat colour approach one stage further and create vector drawn images.

Vector art isn't created as a big grid of pixels, each set to a particular colour, the way photos are stored (known as a raster image). It is created by drawing lines that are stored as mathematical shapes, the same way fonts or typefaces are stored on your computer. The benefit of this approach is that these vector lines and shapes will remain clean and correct however big or small you make them. If you were to try and make the same line in a raster based program (like Photoshop), when you later enlarged the line it would look jagged and ugly. Vector art is inherently clean and elegant and very easy to manipulate and alter, making it an excellent tool for graphic novel art. That's why I'm keen to turn my inked drawings into vector art. That way, I can colour them really quickly and easily and produce a fine colour picture.

The only thing is, up to recently, vectorizing my line art has been a right pain to do. In the past, My usual approach was to import the image into my vector art program (I'm still using Lineform even though it's a dead duck as a product which is a great shame) and trace over the ink lines to create a vector image. I would then filled in the colours to create the colour picture. This though was a very slow process. I'd looked for tools to automate this but they'd all produced a mess of a result.

Fortunately, I found a solution last week. There is a company that has developed an excellent program for turning black and white drawings into vector art. You can see them at For a small quarterly fee, you can upload your inked picture to their website and they'll turn it automatically into a quality vector art version. Hooray!

I can now vectorise my ink drawing. Once I've had the ink drawing vectorized, I open up the new vector drawing in my vector art program Lineform. I quickly select the white areas between the black lines (which are already defined as bounded shapes) and set them to appropriate colours. I then create some areas of shading on my picture. I do this by drawing areas of shade using a graphics tablet pen (I've got a Wacom Intuous 3 tablet). I set these shading areas as black but with 30% opacity, making them a shadow rather than a block of colour. I've found this to be a much better alternative to making the shaded areas a block of a darker colour than the normal areas. This latter approach throws up all sorts of ugly colour mismatches.

Once the shading's complete, I just make a frame, stick in the dialogue box and bob's your uncle, one completed colour picture!

I'm still exploring ways to improve the visual style while keeping up the speed of page creation but I'm pleased with my progress so far.

Stay tuned!