• Tutorial: Digitally Painting a Tree Frog
    Richard Harris, 3 September 2002

    The first thing I do before embarking on any project is to gather as much reference as possible. In this case, however, I had been inspired by a birthday card someone had given me with 3 tree frogs on a branch, which is what I used as my main reference. I also did a google image search too to find additional images as you can never have too much information.

    I decided to draw only one of the frogs on the card as I felt that doing all three would be too time consuming for what was only ever intended to be an exercise. I very carefully drew the frog on plain typing paper with an HB pencil initially, and a 2B later for emphasis. I wasn't concerned with doing any decent rendering at this stage (that comes later), but just trying to be as accurate as possible with my shapes and lines. I very loosely indicated shadow areas too, but without getting bogged down into detail. Many people actually dive right in and lay down the basic shapes by blocking in with paint, much in the same way by very carefully defining the main forms as bold shapes but personally I still need a tight pencil sketch as a solid base to start from.

    If anyone is unsure about this vital step I strongly recommend reading "Drawing on the Right Side of the Brain" by Betty Edwards. There are many techniques in that book which can help you achieve more accurate drawing. Alternatively (and I hope I don't get lynched for saying this) you could trace a photo to get the basic shapes. No one should rely on tracing to do all their drawing with as it obviously could seriously hamper you artistically if you aren't able to draw without tracing, but many many professionals will trace an image to save time on a deadline. If you really want to learn how to draw however you are better off just drawing. It isn't as difficult as you might think -- the key lies in careful observation and patience rather than in any feat of dexterity. As an aside, my actual drawing technique is appalling: lots of little lines rather than nicely defined bold lines (I tend to "feel" my way around with short strokes that build up into longer ones), but I'm not bothered about it here as long as the shapes are accurate.

    I would like to quickly reiterate something I said in the previous paragraph: the key lies in careful observation and patience. This is the fundamental skill in any representational art. The more closely you look at your subject the more realistic your representation will be. By looking and observing you understand, and with understanding you can replicate. You will need to observe the shapes, the underlying forms behind those shapes, the edges, the tones, the colours, the textures and the light.

    Once I am happy with my sketch I scan it in and set it up on a "multiply" layer with very low opacity to use as a template for the painting. From there I quickly painted the background with a large airbrush, this was rough and loose as I didn't feel the need to be accurate with what is essentially a blur!!

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    Tree frog reference material


    Background layer

    Pencil sketch layered on background
  • Blocking In
    The next step is to block in the colours, without a tight sketch for guidance this stage is crucial and should be done very slowly and carefully.

    Once I had blocked in, I then moved in to each area individually and started detailing. Again this isn't really correct, most instructors would advise building up detail gradually over the whole thing but I haven't got to the stage where I can make that method work for me.

    Firstly, I use the pen tool to create masks where the hard edges need to be. I create a path using the sketch for guidance and then by holding down control and clicking on the path in the paths palette (in Adobe Photoshop), I have a selection based on that path that I can use for painting in. I always save the paths for reuse later. The beauty of using the pen tool is that your masks can be edited by moving the anchor points, which makes them very flexible. If you need softer edges you can either feather your selection or save the selection to a channel and blur it or paint in softer edges where required.

    My method of detailing is to determine where the main areas of light and shadow fall within the area that I'm painting and to define them first. I use variations of the base colour and/or brushes set to "screen" or "multiply" to create the areas of light and shadow. The brushes I used here were all hard round brushes set between 10% and 50% opacity. I am experimenting with other brushes but for a clean look I have found these to work best. Using low opacities and blending modes allows to create fairly complex colour steps and blend between many shades. I prefer the hard brushes as they don't have that soft airbrushed look which I'm not keen on.

    The detailing stage is quite slow and gradual. I add texture to my surfaces by painting in random dots or strokes in "screen" or "multiply" modes with a very small brush. As you can see from the detail shots, the painting isn't super-sharp or accurate. It really benefits from being shown at a smaller size and sharpened when finished. I also try to layer glazes of subtle colour over each other, again using blending modes as this adds a touch of chaos and subtlety to the image. By painting my highlights in "screen" mode over the already detailed skin on the frog's legs I was able to achieve a very glossy look. I was also careful with my colours here -- I did some passes in white and some in pale blue to give a sense that the sky is what is being reflected as this is what I thought I could see in the reference. Again using a low opacity brush enabled me to blend between shades.

    The textures on the branch and on the feet where created using the pattern stamp, again at very low opacity and set to "screen", "multiply" or "overlay". this is much quicker than painting the texture bit by bit as I had done on the head. Once I had created a layer of texture I would paint over with the brush again to emphasize light and shadow, then more texture then more paint to create a gradual buildup. I often took snapshots as I went along and after adding a layer of detail I would use the History Brush at low opacity to blend in my new layers of paint with the snapshot of the previous state.

    As you can see the legs are much better than the head, this is because I was learning as I went along and got better by the time I got to the legs!!

    Another point worth making is that in earlier paintings, I would look at the reference and note that colour "a" was next to colour "b" and try and copy that without really analyzing why these colours would be in those places. The result would often look very flat and poorly defined. In this painting I really started to think about light and how it would hit the forms, surfaces and textures and help to define all of them. I use light to define the depth and solidity of the forms and to convey the quality of the surfaces (i.e. wet or dry, matte or glossy).

    After several days of painting and repainting (this took me 4 days from start to finish) I got a stage where I was happy with the image. I then added a Hue/Saturation adjustment layer to tone it down a little as it seems my initial colour choices were a little on the bright side. The image could probably be tweaked further with the addition of a Levels adjustment layer or even a Colour Balance one but in this case I didn't bother.

    "Blocking" in stage.

    Eye detailing.

    Leg detailing.

    Final composition.

    About Richard Harris
    itchy animation is a small company based in Camden Town, London. We can provide a range of creative services from illustration to animation using either traditional or computer generated methods. Based on very strong traditional drawing skills, we can work across a range of styles tailored to client requirements.

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