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What Are the Different Types of Digital Image Processing Techniques?

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  • Written By: Helen Akers
  • Edited By: Jessica Seminara
  • Last Modified Date: 20 September 2016
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Digital image processing techniques are typically classified into three categories. These categories include image generation, enhancement, and restoration. Generation techniques help project and recognize a scanned image, while the process of enhancing an image involves improving contrast, brightness and hue. Restoration techniques help eliminate and correct errors that do not accurately reflect the original picture.

Many scanners that transmit images into computer programs use optical character recognition (OCR) technology. This converts the original image into text that the computer program will recognize. One of the main problems with any type of image processing technology is that some degree of editing is needed. Simple programs allow users to manipulate the image by cropping off unneeded space, changing the tint, brightness, and layout orientation.

Image generation is one of the digital image processing techniques that involves converting an image into some sort of ordered layout. For example, a scanner may pick up an image by creating a reflection. Digitization takes that reflection and attempts to arrange it into a series of pixels. Some forms of digitization make this arrangement by looking for variations in the amount of light recorded from the original image.

Enhancement is a broad category of digital image processing techniques that manipulate a digitized image. Computer programs may allow users to duplicate and change scanned images. For example, a color photograph can be converted to black and white. Likewise, parts of an image can be sliced and transposed into another.

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Common techniques related to image enhancement include changing an image's tint. Some of the more common tint enhancements are related to primary colors, such as red, green, blue and yellow. A dull or faded image can be made brighter, which may eliminate some image or background imperfections. Contrast may be increased or decreased according to the amount of detail that needs to be shown.

Digital image processing techniques can also include restoration. Some scanned images may pick up tears or lines. Noise, which may show up as random dots or streaks, can be eliminated through replacement techniques. Replicas of the average recorded scan line replace defective or missing pixels.

Restoration may also involve the use of digital filtering. This is one of the digital image processing techniques that are used to eliminate dots or image spots. Any pixel that falls outside of an average range of values is typically eliminated when filtering is used. Pixels that fall outside the average range will usually show up as dark or lighter spots on the image.

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indemnifyme
Post 5

@SZapper - Yeah, I think the fact that things that used to take a long time in the dark room now only take a few second really contributes to this problem. Maybe photo places should stop giving consumers less options!

Anyway, I took a digital photography class in college too. We did a little bit of digital restoration. It wasn't too difficult, but man was it tedious. I don't think I could spend me whole day just doing that and stay sane!

SZapper
Post 4

@nony - This is very true. Digital imagine processing can get overwhelming because there are so many options. I have a degree in art with a photography concentration, and I struggled with this in my art. How can you tell when the piece is "done" when there are so many other things you could do to it?

I can see why this would be a problem for consumers as well.

miriam98
Post 3

@nony - Last summer I had the joy of taking some of my grandparents’ old, faded photos and scanning them into the computer, one album at a time.

I was then able to clean up the photos, add some enhancement, and create a photo album DVD for my grandparents on their anniversary.

They were absolutely delighted that I was able to preserve their memories on disc and I had a lot of fun doing it.

nony
Post 2

@SkyWhisperer - That’s a good point. I’d also like to make one observation about digital photos.

Sometimes consumers are overwhelmed by the sheer number of options that they have for retouching their photos. You can do just about any kind of enhancement to a photo, whether it’s a digital photo from your camera or a film photo that you scanned in the computer.

However, before you go crazy making all sorts of adjustments to the image, ask yourself what the final output will be. If it’s going to be digital output, then it doesn’t hurt to enhance the image.

However, if you’re going to print the photo, then you should limit the amount of enhancement that you do. A little brightening and some contrast here and there is okay, but more than this, and the printed output will not look good.

SkyWhisperer
Post 1

I think that one of the most important things for you to remember with image enhancement is the old adage, garbage in, garbage out.

Basically this means that you are limited with how much cleanup you can do with an image, if it’s not fairly clear to begin with. So when I scan photos into my computer, I always check the scanner plate first.

Sometimes I will clean it with a mild cloth to eliminate any of the streaks. In addition to this I make sure that there are no strands of hairs or fine particles or things like that.

Those things get magnified a hundredfold in the finished image. Then, and only then, do I scan the image. Sure, you can do some measure of cleanup, as pointed out in the article, but random noise is hard to eliminate.

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