Let's consider strictly technical aspects of icon creation
1. Lines, angles
One of the vital parts of the image is the outline of the object, i.e. solid line, which separates the object from the rest of the image. When creating normal-sized images, the designer occasionally cares about highlighting of objects with additional outlines. This is unnecessary because of the size: even non-contrasted objects do not mix into a single whole. Pixel graphics is other story. Two solutions are possible: either object and background colors have to be from different sides of the color chart, or the object must be separated from the background by contrast outlines and shadows. I would like to discuss lines deeper.
If we return more to the big-size graphics, we can note that in order to highlight contours, we can use any (including the most complicated) angles, Bezier splines and borders. Anyway, the line will look ideal thanks to anti-aliasing. When shrinking the image dimensions to the size of an icon, situation changes dramatically. When every particular pixel is equally valuable and can change the whole look of the composition, anti-aliasing is just not applicable. It comes that you should consider the possible line slopes.
The slope you select for the line, specifies the step of this line. This means that each line consists of primary elements, the combination of which defines its neatness and esthetics.
For example, a 18-degree slope consists of many tiny 3-pixel lines combined with a 1-pixel downshift:
This is how almost every line looks like. Primary element followed by joining and second primary element. Unfortunately, not each angle creates lines that look look neet and not messy.
For example, here are 25 and 20-degree angles:
It can be easily known which line is more appealing. The 25-degree angle makes a line containing 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 supported by other visual effects, it brings a feeling of messiness: the basic elements have contrast which is too strong to hide from the human sight.
Here we can see the first rule. The most "appropriate" slopes have to make as simple primary elements as they can. Thus, the ideal slopes are 0 and 90 degrees. In those, 1-pixel primary elements are joined without any shift and produce even lines. Less ideal are angles which form primary elements of 1, 2, 3 pixel with 1-pixel downshift. Surely, the lines can not be even, but the human sight will process the image and provide to the user what you intended to show to him. Also, the following angles can be considered correct (but at a stretch): angles with primary elements consisting of different lines shifted by more than 1 pixel.
It is the time to move to another problem. In the last paragraph, I intentionally defined slopes with primary elements of 1, 2 and 3 pixels as acceptable. Such small lines, especially when a large number of them is combined, appear as solid. But what do we see if we change the basic 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 combination of several lines, situated near one another. Hardly any artist wants its creation to look that way. Thus, we have another conclusion: if you use minimal slopes, which produse long basic elements, it must be justified and used with maximum attention.
And, finally, the third aspect I have to tell about lines. I already wrote that the primary element should be as simple as it can.
For example, a 25-degree angle can be produced in the two (sure more of them are possible) following ways:
In the first case the basic element is a 2-pixel line. In the second case, it consists of three elements: 3-pixel, 2-pixel and 1-pixel. The same slope but the image is different. The complex basic element made the line untidy.
Such examples can be produced for about any slope, so in your works, make sure to simplify everything.
It can be stated without an overstatement that the color is the leading element of your work; not suiting or badly matched colors can kill even the best idea. What can we write about the color in icon graphics?
First, there is a certain rule: if the picture looks poor when reduced to monochrome, then the colors that were used are wrong. This rule is valid not only for icons but for the entire graphic design.
Second, you will be unable to use common RGB. Sure, you can select GIF colors only, but this limits you greatly. Gradients, shadows, dithering and many other effects will not be accessible to you.
Third, try to increase the areas of "plain" color. The more evenly colored parts without blurring and jumps your composition has, the more clear it appears. Pictograms are too small and the over usage of special effects makes the image look dirty.
Fourth, gradients. This is a wonderful tool which can improve the appearance of any picture. Other than visuals, gradients are a perfect solution to get rid of the "broken line" effect (lines with too long primary elements). But be careful when applying them because too many gradients can ruin the flat color, and be unable to fit into the gif palette.
Fifth, shadows and highlights. All aspects of using shades and highlights in icon design are completely the same to the aspects of the overall graphic design. The only ine I would like to note: create everything yourself. Don't apply effects, make all shades and highlights in a separate layer and then edit its transparency. If using filters, you rarely know what will it look like. It is unfavorable when you don't control the process of creating of a composition. It is worse if you can't control it if creating icons.
And, lastly, sixth. Tinting is the main aspect of pictogram design, which greatly results the visual appearance of the image. If the green human eye in the icon is sized 1 pixel, increase the color intensiveness. For instance, instead of 0, 131, 159 choose 71, 195, 242. It doesn't matter that the human eye never has this color; in the first case it will look like a gray dot, and in the second example it will definitely be a green eye.
Thoroughly control the picture, do not allow the optical tricks to ruin your work. It is OK if something is not consistent from the technical point of view, but the entire composition must be flawless.
As an example, I pictured the packet of juice located before me. The image has plain color, gradients with broken lines, shadows and flares and nuances.
If I wrote about something bigger than miniature design, this chapter wouldn't fit into a whole book, but the resolution of images restricts fonts too.
The size of letters becomes the leading aspect as opposed to their fineness. Almost in all cases, only if not the letters are the primary part of the composition, the font size has to be decreased to the largest extent possible.
In principle, almost any design company has its exclusive font with little characters. This font can be made in a couple of hours. You can search the internet and collect your own library of very interesting fonts. First of all, I would recommend you to get the DS Pixel and Seventen 7Vedi website as well as the entire set of fonts from the Lakmus Lab website.
If you don't want a new font, small typesizes of Arial and Verdana will work. As a last option, you can create the necessary letters by hand.
There are quite a few rules there. First, letters cannot be less than 5 pixels high or less than 3 pixels wide.
Second, letters cannot use anti-aliasing. It turns the font into an incomprehensible mixture of pixels.
Though, there are no rules without exceptions and the 5-point Arial looks perfectly readable.