Let's discuss strictly technical details of icon creation
1. Lines, slopes
One of the vital parts of the composition is the framework of the object, i.e. rough border, which limits the object from the background. When creating large-scale graphics, the designer rarely cares about defining objects with additional lines. This is not needed because of the scale: even non-contrasted objects do not blend into a single whole. Pixel graphics is different. Two variants are available: either object and background colors have to be from different sides of the color chart, or the foreground should be divided from the background by visible lines and shadows. I would like to dwell on lines in more detail.
If we return again to the large scale graphics, we see that in order to define edges, we can use all (including the most complex) angles, Bezier curves and borders. In any case, the line will appear ideal thanks to anti-aliasing. When decreasing the graphic scale to the small icon size, situation changes greatly. When each single pixel is equally valuable and can ruin the whole appearance of the icon, anti-aliasing is just unreasonable. It means that you should consider the possible line slopes.
The angle you choose for the line, determines the step for this line. Because every line is made of primary elements, the union of which defines its neatness and esthetics.
For example, a 18-degree slope contains many small 3-pixel lines connected using a 1-pixel downshift:
This is how nearly each line looks like. Basic element followed by joining followed by second primary element. However, not every angle makes the line look attractive and not messy.
For example, here are 25 and 20-degree angles:
It can be easily seen which line is more appealing. The 25-degree slope makes a line consisting of equal 2-pixel basic elements. The 20-degree angle has a primary element containing of three lines: 3-pixel, 3-pixel and 2-pixel. The angle is more complicated, thus, if not combined by other visual effects, it creates a feeling of untidiness: the primary elements have contrast which is too strong to escape the human sight.
Here we can see the first rule. The most "appropriate" slopes must make as simple basic elements as they can. therefore, the perfect angles are 0 and 90 degrees. In them, 1-pixel basic elements are combined without any shift and form smooth lines. Less perfect are angles which form primary elements of 1, 2, 3 pixel with 1-pixel downshift. Of course, the lines can not be smooth, but the human sight will process the picture and provide to the viewer what you meant to show to him. Also, the mentioned angles can be considered correct (but at a stretch): slopes with primary elements made of different lines shifted by more than 1 pixel.
It is the time to move to another issue. In the last paragraph, I purposely defined angles with primary elements of 1, 2 and 3 pixels as correct. Such small lines, especially when a large amount of them is combined, look like a single whole. But what happens if we increase the primary elements to 10 or 20 pixels?
Here is an example:
It can be obviously noticed that the line loses its integrity. It is not a single line anymore; it is a set of several lines, situated near one another. Hardly any artist wants its creation to look inconsistent. So, we have the second conclusion: if you use minimal angles, which produse long primary elements, it must be reasoned and employed with maximum attention.
And, finally, the third aspect I have to mention about lines. I did write that the basic element should be as simple as possible.
For example, a 25-degree angle can be drawn in the two (of course more of them are possible) following ways:
In the first picture 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 basic element made the line untidy.
This examples can be produced for almost any angle, so in your projects, try to simplify everything.
It can be stated without an overstatement that the color is the leading element of your work; improper or badly balanced colors can ruin even the most creative idea. What can we write about the color in icon graphics?
First, there is a clear rule: if the image looks poor when converted to monochrome, then the colors that were chosen are wrong. This rule is valid not only for icons but for the whole graphic design.
Second, you will be unable to use safe RGB. Sure, you can use GIF colors only, but this ties you hand and foot. Gradients, shadows, blending and many other effects will not be accessible to you.
Third, try to enlarge the portion of "flat" color. The more evenly colored parts without diffusion and jumps your picture has, the more clear it appears. Pictograms are too tiny and the excess usage of complex effects makes the image look messy.
Fourth, gradients. This is a great instrument which can improve the appearance of any picture. Besides esthetics, gradients are a perfect solution to abolish the "broken line" look (lines with too long basic elements). But be careful when applying them because too much gradients can kill the flat color, and be not suitable for the gif palette.
Fifth, shadows and flares. All rules for applying shadows and highlights in icon making are completely the same to the aspects of the overall graphic design. The only thing I have to note: draw everything yourself. Don't apply effects, make all shades and highlights in a different layer and after that edit the opacity. If using effects, you rarely know what will it look like. It is bad when you don't control the making of a project. It is worse if you don't control it when creating miniatures.
And, lastly, sixth. Nuancing is the main detail of pictogram design, which largely affects the esthetic appearance of the image. If the green human eye in the icon has the size of 1 pixel, increase the color saturation. For example, instead of 0, 131, 159 choose 71, 195, 242. It is indifferent that the human eye never has this color; in the first example it will look like a gray dot, and in the second one it will definitely be a blue eye.
Thoroughly control the picture, do not let the optical illusions to spoil your design. It is acceptable if something is not consistent technically, but the whole picture must be flawless.
As an example, I drew the pack of juice located in front of me. The image has plain color, gradients with broken lines, shades and flares and nuances.
If I talked about something other than pictogram creation, this part wouldn't fit into a whole book, but the resolution of pictures restricts fonts too.
The resolution of letters is the main issue as opposed to their beauty. Almost in all cases, only if not the letters are the primary part of the project, the text size must be reduced to the largest extent possible.
In principle, virtually any design studio has its exclusive font with little letters. This font can be created in a couple of hours. You can browse the internet and make your own library of very nice fonts. First of all, I advice you to get the DS Pixel and Seventen 7Vedi webpage as well as the entire series of fonts from the Lakmus Lab website.
If you don't want a new font, little typesizes of Arial and Verdana will work. As a last option, you can draw the needed 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 turns the text into an unrecognizable set of pixels.
Though, there are no rules without exceptions and the 5-point Arial appears rather understandable.