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Graphic Formats

Graphic Formats
Created by: Jorgen Bodde

In this weeks' lesson we will be learning about the different types of images and what graphic format is best to save them into.

Introduction to art: When you play around with Paint Shop Pro, you can make all kinds of art. It's not wise to save all types in the one and only graphics-format you think is the best, because it does so well on the photos you own... If you have clipart, you don't save that in the JPG-format! Like that, there are more types that should be saved in a format best suited for that type.

These are the five different types of art which are used the most by people all around the world. Each one will briefly explain what each type of art is all about, and tell you which graphical format is best suited for saving your art to disk.

Line-Art: This type of computer-art is called Line Art because it only uses two colors, black and white. You should convert your picture to "black and white" (2 colors) whenever you decide not to use more colors, like line-drawn images, or black and white scanned images. This gives a considerable amount of compression-gain.

Never save your line-art pictures to disk using the JPEG or JPG (Joint Photographic Experts Group) compression algorithm. This graphic format is only used for complex images like photos, and will damage your line-art image because it uses a lossy compression method (information is lost during compression). Furthermore, when you reload - edit - and save your images too often with the JPEG format, it will damage your image even more, because it loses tiny bits of information every time you save it after reloading. However, when you don't reload the image every time you save it, there's no problem because the original image is still in memory.

The best graphic format to use for Line Art, is PNG (Portable Network Graphics). Out of own experience I know that the PNG format compresses at least 10% better than the GIF-format (Graphic Interchange Format). Version 4 browsers are starting to support PNGs and at this point in time we have no information about PNG support in versions 5 and 6 of web browswers so it might be worthwhile to save them as GIFs instead.

But try it out and see what you think.

Cartoon Art: This isn't the proper name for this type of art. The reason why we are calling it "Cartoon Art", is because it's actually a line art image with colors added. The amount of colors used lies between 16 and 256 and the the image isn't complex at all. It has lots of large surfaces filled with one or more colors without any use of gradient fills or irregular and complex patterns. You could compare this art with a cartoon on TV. Just some colors and some shade-colors, and that's it. Because it looks a bit like Line Art, it's really advisable that you should never use the JPEG (Joint Photographic Experts Group) compression algorithm (see Line Art for explanation).

Also here you could say that PNG (Portable Network Graphics) is the best graphic format to use. It also supports "Interlaced" and "Non Interlaced" image saving like the GIF (Graphic Interchange Format) does. If you don't use the "Interlaced" function (which is only useful on the WEB) don't choose it. This function slightly increases the size of your saved image because it stores your image using a different algorithm. Also a nice option in the PNG format is the support of True Color (16,7 Million Colors). This could be nice to use if you ran out of the palette of 256 colors (which is only 8 bits). The GIF-format doesn't support this option.

Again, try the different formats just to see what you think.

Sketch-Art: When you collect model sheets or cartoon sketches, you know what "Sketch Art" is. It's usually a greyscaled image with drawn pencil-lines which aren't erased, or converted to Line Art. This is a very unique type of art and can give nice results because you can make the shadings yourself using your pencil instead of different colors (this can be done in a future stage of the drawing-process).

Greyscaled images do not contain more than 256 different values (and if they do, it's not really a greyscaled image!). At this point, you could consider using two types of graphic formats, namely; The JPEG format (Joint Photographic Experts Group) and the PNG format (Portable Network Graphics). The decision of which one to use, lies in the complexity of the image. When there are much sketched lines and pencil-shaded surfaces, it's advisable to use the JPEG format. When only simple lines are drawn with almost no pencil-shaded surfaces and thin sketched lines, you should use the PNG format. Be advised about the JPEG format. It uses a lossy compression algorithm (see here for explanation). For this type of art, there isn't really a format which does best. But if you decide to modify the sketched picture later on, you should save it as a PNG image during the time you modify it (because there's no information-loss with PNG). When you're done, save it as a JPEG image.

Please note that if you use the greyscale function in PSP it is only 256 colours. Also try saving it as a GIF just to see what it is like.

Paint-art: Scanned paintings and nice Manga-pictures have a few things in common. They use an awful lot of colors, and complex lines, shades and surfaces in the drawing. Every painting, or drawn image you scan can be considered "Paint Art". The amount of colors isn't quite the reason why people choose to use the JPEG format (Joint Photographic Experts Group) here. It's more the complexity of the drawing (or painting) itself. It's not a problem to save your painted art to disk using the PNG format (Portable Network Graphics), but all irregular patterns and color-shades won't be compressed using this format, and this will create a big file on disk.

However, if you are still editing your painted (or drawn) image, it's wise to save your image to disk using the PNG format to keep your image free of information loss. The JPEG format uses a lossy compression method, and editing - saving - reloading your image every time, will damage your image badly! Only when your picture is done, save it as a JPEG file. This format is really good on photo's and painted art.

GIF format is definitely not the option for saving this type of art as. But just for the sake of it, try it to see what the results are.

Photo-Art: A scanned photo (greyscale or color) is called "Photo Art". Whenever you scan your photo there isn't much of a chance it will be edited in the near future. So it's safe to say that you should use the JPEG format (Joint Photographic Experts Group) here to store your images to disk. Be advised that if you decide to retouch your images more than once, the quality of the photo decays. Every time you load - edit - save your image, a small bit of information is lost, because the JPEG format uses a lossy compression method.

However, If you are going to work on it in the future, then saving as a PSP (Paint Shop Pro working file) or as a PNG is a good idea. PSP is a good format if the image has layers as this format will preserve the layers whereas other formats do not.

If you want to have an animation with or without a transparent background then PNG is an excellent format to save the image as with the added bonus of 16.7 million colours being supported. However, as stated before, a lot of browsers do not fully support PNGs. So if the animated image with or without a transparent background is for your web page, then GIF is the best option. Do note, however, that GIFs only support 256 colours.

To see a comparison, click here to go to the Graphics Format Performance Table page.

Stay tuned. Next weeks' lesson is Changing Image Sizes.