Scaling an image for use on a web page significantly helps how fast the web page loads when you search on Google. The golden rule is not to use larger images than you need.
In order to optimize your images as best as possible, you may want to use an image editing program. There are many of them on the internet and many of them are free. Here are some links where you have the option to both crop and scale images:
But, how do you reduce the size of an image?
It is important to know that there is a difference between cropping an image and reducing the size of an image. When you crop an image, you cut away parts of the image. When you reduce an image, you shrink the image but keep the proportions and the whole image. In order for this not to cause the image to be stretched or squeezed together, it must be reduced according to something called Aspect ratio. Aspect ratio maintains the ratio between the height and width of the image, no matter how much you shrink it.
So that you don't have to sit and calculate the aspect ratio yourself, you can, as I said, use an image editing program. All you do then is determine either the height or the width of the image, and then the program calculates the Aspcet ratio for you.
Reduce the resolution of an image
This can be a little confusing, but there is a difference between reducing the size of the image in pixels or percentage and reducing the resolution of the image in pixels. Then we are talking about size in Kilo Byte (KB), MegaByte (MB) or Giga Byte (GB)
The more pixels an image has, the clearer and clearer it becomes, so reducing the resolution of the image will cause some to become a little more blurry. This usually doesn't mean much on the web, since images are rarely that big. But it has a lot to say about how quickly your website loads them. Large images take longer to load than smaller ones.
Can you scale an image up to make it bigger?
As I said, pictures are made up of pixels. If you scale up an image so that it becomes larger than it is originally, it will pixelate and become blurred. Therefore, it may be a good idea to always save on the original of the image in addition to what you clear down. You then have the option to enter the image in a larger format if what you have entered turns out to be too small.