Technical Info About Digital Art

Resolution, Dpi, Radio... All are frequent concepts in digital artwork and pre-press, but at the same time, a very imprecise theme for some people. Ok, let's add some light...

The RESOLUTION is the quality of an image expressed in numbers, in the case of "bitmaps" (Images that quality depends directly from the DPI -Dots per inch-) to more quantity; clearer will be the image. In our computer's screen we only can be able to see 72 DPI, the standard for on-line images. But if we work an image for Offset printer method the standard is usually 300 DPI. You can use 150 DPI, just if the artwork is bigger than 20"x 30".

I define the resolution that I need from my artwork using this simple formula: LPI x 1.8

LPI (lines per inch) is the measure of quality from printed images in the Offset, and like in the DPI to more quantity; clearer will be the image. If our image will be printed using 133 LPI, then our minimal chosen resolution will be 239.4 DPI (240) because 133 x 1.8 = 239.4. Always remember that we can decrease the resolution of an image (from high resolution to low resolution) but no vice versa; we can add some effects to the image to hide the pixelation, but never just change the image size in a forced way... We'll deteriorate the image in this process.

If you've a low resolution image and you need to work in high resolution, is time to use the INTERPOLATION: This is when we modify the resolution of an image working directly in the size of the image, but maintaining the quality at the same time. If our image has 150 DPI and we take it to 300 DPI, the final size will be the 50%; cause 150 is the half part of 300. We need to pay attention here, cause the more important is not the resolution, is the ASPECT RADIO: The resultant number that we obtain when we divided the more largest number of resolution of the image by the smallest. If our image has 1200 x 1500 pixels then the radio for this image is 1500/1200 = 1.2.

A good example of this is the images that I've in my deviantART section, images originally with a resolution of 1200 x 1500 pixels at 300 DPI (for 10.16 x 12.07 centimeters) If I resize the image to 72 DPI and still use 1200 x 1500 the size will vary to 42.33 x 52.92 centimeters but the quality will be the same (Interpolation!). This is another important detail, cause we can take low-resolution images but with big size (like the pictures from digital cameras) and using this formula, have a decent resolution for an Offset reproduction artwork.

Well... I hope this tutorial can be useful for you all. The information that I've posted here aren't exactly rules, I just express some things that I have learned for experience.