| D i g i t a l I m a g i n g |
| Links for Digital Images Processing: (Freewares/evaluation - Tested and recommended) IrfanView - Organize, convert and basic edit features Neat Image - Noise reduction and sharpen filtering Replig6 - Thousands of effects that can be customized XnView - Good editor with basic features |
| Using digital images involves some knowledge to get a good quality result without creating files that are too big. The use of images has always been limited by memory consumption. As the computers grow in capacity, this is becoming less important and a heaven for those less qualified users that create texts with 25MB and try to send them by e-mail. Fortunatelly most servers won' let such a big file to be sent. For each type of image, there is a resolution, depht of color and file type that will fit well for most of the cases. Some experimentation may be done to find the best solution for a specific case. Using images with MSOffice programs involves many tricks also. Usually things aren't the way they look like. This text is separated in sections, each of them involving one step of the process. |
| See also: Digital Image Processing Hints - Some basic hints on how to edit photos |
| Section 1: Acquiring the image Scanning an image requires the correct settings depending on the type of image and the kind of use for that image. The table below will be suitable for most cases. If the image will be edited, the best is to store temporarily the image in a loseless (BMP/TIFF) format while it is being edited until the image is ready. Latelly to store on the computer, choose one of the suggested formats, preferably the one that appears first on the table. The table indicates the minimum required resolution and DPI that will result in a good quality image. The first two lines indicate the resolution to store whole pages in digital format in a very compact way and well readeable. The multi-page TIFF files are easy to manipulate and read on the computer and can be used to store a whole book. Small drawings can be inserted in documents to make them more easy to understand, and will not consume much memory. There is a big difference between the resolution of the computer screen (72/96 DPI) and the resolution used by the printers. If the image will be seen only on the computer screen, a lower resolution can be used resulting in good quality. But if the same image will be printed, the result will be very poor for screen resolutions, because the printers do not create milions of colors as the screen. They creade midtones with disperse points that can result in a very poor quality if the image does not have at least 200 DPI. The maximum resolution human eye can capture at the normal reading distance is 600 DPI, which is indicated to print photographies. |
| Section 2: Editting the image Depending on the type of image used and the task to be performed, a suitable software should be selected. Some of them already come with the operational system and others may be obtained for free on the web. Typically they do not perform all tasks, so you will need to use each one for certain tasks. The use of a filter to de-pixelize a photo will reduce the image file by about 25%. The best program to do it is Neat Image. |
| Section 3: Using the image An image may be used directly in its stored format or may be inserted in a document or presentation. It may also be printed. The Office programs have capacity to compact (zip) images. Consequently, for those types indicated as BMP (zipped) in the table above, you may paste a BMP direcly in the file and it will be compacted to result in a small document. The MS Office programs have some tricks because an image is not usually just an image for them. |
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