|
| |
HaloHalo (I am not here refering to the Halo video games!) are undesirable artifacts that can occur when you take an anti-aliased image on one background, and try to change the background. What happens is that a trace ("halo") of the original background may be left around the new image.I will demonstrate this using by using an anti-aliased image (actually a clip art) on a green background and attempting to change the background from green to blue. However, halo can in fact occur regardless of the original background (even if you start with a white background). All that needs for halo to occur is:
Let's start by looking at my anti-aliased image on a green background. On the left, the image is shown at actual size, on the right, I have zoomed into a small section of the image so you can see in more detail what is going on.
If you look carefully, at the zoomed in area in the above, you will see that there are some green tinted pixels around the man's picture (on the zoomed in version, most noticeably on his shoulder and the bottom part of his hair), which do not quite match the main green background color. This is the result of anti-aliasing the picture with the background. Now, what happens if I paste the image on to a new background (setting the original's green background color to be transparent):
You should now clearly be able to see the halo. The green tinted pixels which were not quite the same color as the main green background (because of anti-aliasing) have been left behind - giving rise to a halo effect. This is because when I turned the main green background transparent, these pixels, having a slightly different greenish color, did not become transparent. How can we avoid halo? There are a number of ways:
Related Pages on this site:
Related Books:
|
|||||||||||||||||||||||||||||||||
| †Disclosure: Advertising Link(s): Our company may receive a payment if you purchase a product/service after following this link. Disclosure: Our company's websites' content (including this website's content) includes advertisements for our own company's websites, products, and services, and for other organization's websites, products, and services. In the case of links to other organization's websites, our company may receive a payment, (1) if you purchase products or services, or (2) if you sign-up for third party offers, after following links from this website. Unless specifically otherwise stated, information about other organization's products and services, is based on information provided by that organization, the product/service vendor, and/or publicly available information - and should not be taken to mean that we have used the product/service in question. Additionally, our company's websites contain some adverts which we are paid to display, but whose content is not selected by us, such as Google AdSense ads. For more detailed information, please see Advertising/Endorsements Disclosures Our sites use cookies, some of which may already be set on your computer. Use of our site constitutes consent for this. For details, please see Privacy. Click privacy for information about our company's privacy, data collection and data retention policies, and your rights. Contact Us Privacy Terms Of Use Advertising/Endorsements Disclosures Copyright © 2005-2020, Answers 2000 Limited In Association With Amazon.com Answers 2000 Limited is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. In Association With Amazon.co.uk  Answers 2000 Limited is a participant in the Amazon EU Associates Programme, an affiliate advertising programme designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.co.uk. As an Amazon Associate, our company earns from qualifying purchases. Amazon, the Amazon logo, Endless, and the Endless logo are trademarks of Amazon.com, Inc. or its affiliates. CERTAIN CONTENT THAT APPEARS ON THIS SITE COMES FROM AMAZON SERVICES LLC. THIS CONTENT IS PROVIDED 'AS IS' AND IS SUBJECT TO CHANGE OR REMOVAL AT ANY TIME. CERTAIN CONTENT THAT APPEARS ON THIS SITE,COMES FROM AMAZON EU S.à r.l. THIS CONTENT IS PROVIDED 'AS IS' AND IS SUBJECT TO CHANGE OR REMOVAL AT ANY TIME. All trademarks are property of their respective owners. All third party content and adverts are copyright of their respective owners. Some graphics on our web sites are Copyright (C) 1997-2000 Hemera Technologies Inc., and used under license. All such pictures are provided for viewing purposes only and are not to be saved or downloaded. All such pictures of recognizable individuals are models and used for illustrative purposes only, and not meant to imply any association or endorsement of said individual with any product or service. |
|
