Let's consider strictly technical details of icon making
1. Lines, angles
One of the most important parts of the image is the framework of the object, i.e. rough line, which limits the object from the rest of the image. When designing large-scale images, the artist rarely cares about defining objects with additional outlines. This is not needed because of the size: even low contrast objects do not mix into a single whole. Pixel graphics is different. Two solutions are possible: either object and background colors have to be from opposite sides of the color wheel, or the object should be divided from the background by contrast lines and shadows. I will dwell on lines in more detail.
If we think again to the large scale graphics, we can note that in order to highlight edges, we can use any (even the most complex) angles, Bezier splines and borders. Anyway, the line will appear ideal thanks to anti-aliasing. When shrinking the graphic scale to the size of an icon, situation changes dramatically. When every particular pixel is equally valuable and can change the whole look of the icon, anti-aliasing is just not applicable. It means that you have to consider the possible line slopes.
The angle you select for the line, specifies the step of this line. Because each line is made of basic elements, the union of which determines its neatness and visual appeal.
For example, a 18-degree slope contains many tiny 3-pixel lines connected using a 1-pixel downshift:
This is how almost every line looks like. Primary element followed by joining followed by second primary element. However, not every slope makes the line look attractive and not messy.
For example, here are 25 and 20-degree slopes:
It can be easily seen which line is more attractive. The 25-degree slope makes a line consisting of even 2-pixel primary elements. The 20-degree slope has a primary element containing of three parts: 3-pixel, 3-pixel and 2-pixel. The angle is more complicated, therefore, if not combined by additional visual effects, it brings a feeling of messiness: the basic elements have contrast which is too strong to hide from the human sight.
Now we can see the first conclusion. The most "correct" slopes have to make as plain basic elements as possible. Thus, the perfect slopes are 0 and 90 degrees. In them, 1-pixel basic elements are combined without any shift and form even lines. Less ideal are angles which form primary elements of 1, 2, 3 pixel with 1-pixel downshift. Of course, the lines can not be even, but the human brain will process the image and present to the viewer what you intended to show to him. Also, the mentioned angles can be considered acceptable (but at a stretch): angles with primary elements made of different lines shifted by more than 1 pixel.
It is the time to touch another issue. In the last paragraph, I intentionally defined angles with primary elements of 1, 2 and 3 pixels as correct. Such tiny lines, especially when a great amount of them is joined, appear as a single whole. But what do we see if we increase the basic elements to 10 or 20 pixels?
Here is an example:
It can be obviously noticed that the line loses its solidness. It is not a continuous line anymore; it is a combination of different lines, situated near each other. Hardly any artist wants its composition to look inconsistent. So, we come to the second conclusion: if you use small slopes, which produse long primary elements, it must be justified and used with great attention.
And, finally, the last aspect I have to tell about lines. I did write that the basic element has to be as plain as it can.
For example, a 25-degree angle can be drawn in the two (of course more of them are possible) following ways:
In the first case the basic element is a 2-pixel line. In the second picture, it consists of three elements: 3-pixel, 2-pixel and 1-pixel. The same angle but the image is different. The complex primary element produced the line untidy.
This examples can be produced for about any slope, so in your projects, try to simplify everything.
It can be stated without an exaggeration that the color is the main aspect of your work; improper or badly matched colors can ruin even the best idea. What can we say about the color in miniature graphics?
First, there is a clear rule: if the picture looks bad when converted to grayscale, it means the colors that were chosen are wrong. This rule is valid not exclusively for icons but for the entire graphic design.
Second, you will probably unable to use safe RGB. Sure, you can select GIF colors only, but this ties you hand and foot. Gradients, shadows, dithering and many other tricks will not be accessible to you.
Third, try to increase the portion of "flat" color. The more evenly colored parts without diffusion and jumps your composition has, the more clear it appears. Pictograms are too small and the excess usage of special effects makes the image look dirty.
Fourth, gradients. This is a wonderful tool which can improve the look of any project. Besides visuals, gradients are an ideal way to get rid of the "broken line" look (lines with too long primary elements). But be careful when applying them since too much gradients can kill the flat color, and be not suitable for the gif palette.
Fifth, shadows and highlights. All aspects of using shadows and highlights in icon making are totally the same to the aspects of the overall graphic design. The only ine I have to note: draw everything yourself. Don't use filters, make all shades and highlights in a separate layer and then edit the opacity. If applying filters, you rarely can predict what will it look like. It is unfavorable when you can't control the process of creating of a composition. It is worse if you can't control it if creating icons.
And, finally, sixth. Tinting is the key detail of icon creation, which greatly results the esthetic look of the composition. When the green human eye in the image is sized 1 pixel, increase the color saturation. For instance, instead of 0, 131, 159 choose 71, 195, 242. It doesn't matter that the human eye can't have such color; in the first example it will appear like a gray dot, and in the second case it will definitely be a blue eye.
completely control the image, do not allow the visual illusions to ruin your work. It is OK if objects is not consistent technically, but the whole picture must be perfect.
As an example, I drew the packet of juice located in front of me. The image has flat color, gradients with broken lines, shadows and flares and nuances.
If I wrote about something bigger than icon creation, this chapter wouldn't fit into an entire book, but the resolution of images ;limits fonts too.
The size of symbols becomes the main issue as opposed to their fineness. Nearly in any case, unless the letters are the primary part of the composition, the font size has to be reduced to the greatest extent possible.
In principle, almost any graphic company has its exclusive font with small letters. Such a font can be crafted in several hours. You can browse the web and make your own collection of very interesting fonts. Primarily, I would recommend you to download the DS Pixel and Seventen 7Vedi website and the whole set of fonts from the Lakmus Lab website.
If you don't want a new font, tiny typesizes of Arial and Verdana will work. As a last option, you can draw the necessary letters by hand.
There are quite a few rules there. First, characters cannot be less than 5 pixels high or less than 3 pixels wide.
Second, letters cannot use anti-aliasing. It transforms the text into an unrecognizable set of pixels.
Though, there are no rules without exceptions and the 5-point Arial appears perfectly readable.