Which are copyright images and which are not?

There's no perfect way to check the image you are using is a copyright image or not. More than 90% images that are available on the net is copyrighted images. The best way to be safe while using images on your blog is to capture the images you require by yourself. This is best option you should opt for.

Everybody knows it is illegal to use images of others without their consent in our webpages. It is a fact that finding a copyright free image is hard. But we have to, as we are all not be able to produce photos ourselves for our websites. So the remedy is to use "creative commons" photos.

There are many methods to find creative commons photos. For example using Flickr one can search " creative commons and use commercial purpose" for legal use of photos.

Never ever use any image which u have any doubt about copyright issue. You can freely use images from Wikipedia commons by giving credits to the original photographers.

If any of the image says copyright protected, don't use it.

There are a few ways to find whether the image is copyrighted. Follow these simple rules -
1.Look out for possible overt indications to the copyright. Some of the indicators could be - Watermarks that could be placed covertly, or on the image itself. Copyright symbol ( placed at any corner of the image, or in the title indicating the name of the person holding copyright.)
2. If you found the image in an website or book, try to contact the website owner or publisher of the book, if you can't find the credit beside the image itself. Maybe they will be able to help you to locate copyright owners.
3. Try searching for the photographer online so that you can contact him/her to seek permission to use the image.
4. Go for GNU or CC (Creative Commons) images that allow reuse for free, but under some conditions.
However, it should be clearly understood that that there is no foolproof method to flawlessly identify whether an image is copyrighted or not. Best rule would be to believe all images - not belonging to you - are copyright protected & try to get permission from concerned person(s).