Pictures can be with a smaller size when we need bigger one. For example pictures taken with a mobile phone, received from a friend or whatever.
Is possible to make pictures bigger, but usually will be a quality loss. This is because every image has a number of pixels. If original image has a number of 1000 pixels and we enlarge it to be bigger, those 1000 pixels will be redistributed to a larger area. The bigger will be, the lower quality final image will have.
When you make pictures bigger, test different sizes and view final results to see if the quality is what you expect.
Usually results are good, for example an image with 400x200 pixels, if we make it double, will look ok, but if we enlarge it 10 times or more, quality loss may be visible.
1. XnConvert is a free good software, that will enlarge or resize pictures to bigger sizes preserving good quality.
Install it and open it. Add image files or folder with images. You will see images on the main interface
Click the Actions tab and Add action (from here you need to choose Resize option).
Select a custom preset, for example enlarge your image by 200%, 400% (2 or 4 time bigger).
If you do not find a comfortable custom preset, enter desired width and height in pixels.
After you have set desired options go to Output tab and choose the folder where enlarged images will be saved.
Click Convert and your pictures will be enlarged to desired size. If you have no quality loss and your pictures looks ok, you can set bigger width and height.
This application is good to make other operations to pictures, like convert to another format, crop, add effects and many more.