Resizing an image using Photoshop
Accessing photoshop.
This is not guaranteed. You do not need to spend $20 a month unless you are really into this. Consider altenatives https://itsfoss.com/open-source-photoshop-alternatives/ .
You adjust an image to make it suitable, sometimes its too large, sometimes its too small. Its impossible to consider all the alternatives for this scenario.
Assuming you have photoshop
The screenshots below are on Photoshop CS5.
Open your image and access the image shown
You should get the menu below.
So this image takes up 34 mb.
It is currently 2816 pixels across and 2112 high. You can change the units. Altering this makes the file size bigger or smaller
It is currently 100 cm by 74.5 cm. Thats huge. Do you need it that big? If you made it smaller, it will take up less memory
It is currently 72 pixels per inch. That is fine for web work as it doesnt need to be super detailed. 300 pixels per inch is the minimum for detailed print work.
All of the above are alterable. If you want to keep the image in the same proportions, dont click on the chain, if you do, then you can change the scale of the image, (adjust the height bit not the width and vice versa)
Changing the file type
The standard for a web image is a jpg. Sometimes you need to change a file extension.
in photoshop
Go to File > SaveAs
You get the following. You can see the attached image is a .png file. Simply change it to .jpg and follow the instructions through.
Compression
Compression is squashing a filesize down without changing its size. There are online tools to do this for you. Some examples include.