Canon EOS digital cameras use an anti-aliasing filter that improves color rendition. This filter causes a softening effect that slightly reduces the sharpness of the image. To improve the sharpness of the image, you should apply an Unsharp Mask Filter in Adobe Photoshop.
Here are the recommended settings for the Unsharp Mask Filter:
Radius: 0.3 pixels
Threshold: 0 pixels