When I take photos, I have the same kind of artifact like in this photo (but not as much) :
What is the cause of this artifact and how can I prevent it ?
An example from my camera, note particularly the pamphlets on the bricks near the bottom:
Thank you
Fortunately for you it is essentially certain that the bus image problem and what your camera is doing are different. Your camera's issue is standard lens chromatic aberration which is part of what you get at that price-performance level and it can often be minimised once you understand what causes it.
However, the bus image contains both chromatic aberration plus indications of a more severe problem.
In the bus image, and in other images from the same photographer, it can be seen that the images have a strong red "bleed" on the "low" side of light to dark horizontal transitions and green "bleed" on the "low" side of dark to light horizontal transitions. It is not obvious whertehr this is a camera problem or due to something in his processing system, but a camera sensor or processing issue seems most likely.
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Your issue is "normal" CA (chromatic aberration) - not nice to have, but at least well enough understood.
Your example image has conventional purple-green chromatic aberration occurring on high contrast edges.
Seen most clearly on horizontal lines here
And on verticals here:
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DPREVIEW COMMENT
DPREVIEW are one of the top internet camera review sites
(IM & many others HOs). So their comments are liable to carry more weight than most reviews. I've copied some of their comments re the Canon SX210IS below.
Arguably the most important things to consider about a compact camera's performance are the consistency and accuracy of its metering, white balance, and AF systems, and the Canon performs very well in all of these respects. A slight tendency to overexpose in bright contrasty conditions is mildly annoying from a critical image quality point of view, but it does at least ensure that prints made straight from the camera are bright and punchy.
Our main concerns with the SX210 IS are actually ergonomic. As a picture taking tool, it's a fine camera, although at close to $350 it isn't cheap, and it faces strong competition from feature-rich competitors like the Samsung HZ35W and Panasonic Lumix DMC-ZS7, both of which offer a 24mm equivalent wideangle.
We like: Large screen, decent image quality at low ISO settings, fast and responsive operation, reliable metering, AF and WB.
We don't like: Annoying pop-up flash, poor use of screen real estate in shooting/review modes, poor detail capture at high ISO settings, fiddly zoom control.
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More on the bus image and other photos from the same photographer:
Here is the source of the original bus image - Wikipedia. Photographer P Poschadel.
And here is a completely different image by the same photographer.
It can be seen to have the same "bleed" effect on some only horizontal boundaries. He tends to get red or purple "bleed" on light to dark transitions and green "bleed" on dark to light transitions (as in the bus image) . Thus -
It also has strongish but conventional CA on some verticals.
