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IMAGING

• Acquisition
• Bitmap and Vector
• Resizing
• Compression
• Formats
• Color
• Comparisons
• Text as Image
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• Imaging Index

Image Acquisition

Whatever you do, DON’T ‘use‘ images off the Web, unless they are there for download. Plain and simple, it‘s stealing. Just don’t do it. As far as the ART302+ course goes, it’s grounds for discipline.

Source images come in one of two types: bitmap or vector. Bitamp are continuous tone, or photographic. Vector are generally flat areas of color. A more in-depth look at the two can be found on Bitmap and Vector.

Whether they come from a digital camera, a scanned print, or a stone tablet, images used on the web must be digitized, and then (usually) converted to a suitable format, usually GIF, JPEG, or PNG. In the case of digital cameras, the format may not even need to be changed, as many cameras use JPEG as their basic format. However, figure that you will have to mess with all images, one way or another.

With this in mind, images should begin bigger – in size and probably resolution – than we will use in the end.

Source Images

A source image is usually larger, and most often has more resolution than is needed for web. That is a good thing. You want extra data when you are making corrections, and digital images do not (neccessarily) lose quality when making them smaller. Depending on how the image is acquired, you can specify the original resolution.

Digital Cameras

If you are getting images with a digital camera, use the highest setting available. This may be a high-quality JPEG, TIFF or RAW. Either way, use the highest you can (buy a bigger storage card if you need to). TIFF and RAW formats have the advantage of lossless compression, which means you don’t lose pixels along the way. Additionally, if you can, turn off any image sharpening. This can really hurt the end product.

Corrections and tweaking should be done in an image editing application, not the camera, so get the images, get them off the camera, and into your image editor.

Scanners

There are really two types of scanners we are talking about here, flatbed and film. If you are using a flatbed, you just need to specify enough resolution for the size you want your image. (This will probably mean using advanced mode, at least with Epson scanners). You should generally be safe using between 150 and 300 pixels per inch. In the end, most of this will not be used, but the extra pixels wil make correcting and adjusting better.

If you are using the flatbed to scan film (negatives or slides), at least double the resolution. This because your image will be much smaller to begin with (roughly 1 × 1.5 inches), and it will probably need to be scaled up before it is used.

A dedicated film scanner wil only scan at the 1 × 1.5 inches (for 35mm), but probably at a very high resolution (4000ppi?). This gives you a fairly large file to start with, which is fine.

Either way, as with the camera, turn off sharpening (may be called Unsharp Mask), and leave corrections for the image editor.

Vector

Vector images are generated by a vector drawing application. Illustrator has it’s own Save for Web function. Additionally, vector images can (usually) be opened in an image-editing application, and from that point dealt with as bitmaps.