When you upload images to Blogger, you are asked to choose a size - small, medium or large.
It doesn't matter what size your original image is, as long as it's bigger than the pre-set sizes; Blogger re-sizes it and displays it in your chosen size on screen. If you want to see the uploaded image at full size, just click on it.
With that in mind, you may prefer to re-size the image before you upload it, so that you have control of how it is re-sized.
Here are the dimensions of the three Blogger image sizes:
Small image
width=200 pixels; height=150 pixels
Medium image
width=320 pixels; height=240 pixels
Large image
width=400 pixels height=266 pixels
The three images above were uploaded at their original "camera" size (2048 x 1536 pixels), and re-sized by Blogger.
The three images below were re-sized to the standard Blogger sizes in Photoshop and adjusted to improve the quality.
