Photo and Image Resolution when regarding photos and digital designs is a little confusing when first starting out. When you're providing certain image sizes you want to ensure that the quality is great when providing it to your customers. With Vector images (See this blog post on file types), you can change the size and you won't lose resolution, however with raster images (like jpegs and pngs) you are stretching the pixels and the photos tend to get blurry. 

So let's get a few definitions out of the way

Resolution

Resolution is the amount of detail an image holds. High resolution images have clear, crisp lines and are more detailed. Lower resolution, color loss is apparent and you have a blurry or pixelated look to the larger image. 

There are two types of resolution that always get confusing to most. Screen resolution and print resolution. Screen resolution never changes. There are two definitions to take note of dots per inch, or DPI, and pixels per inch, or PPI, are the two words you will hear thrown around. 

Screen Resolution

Screen resolution is measured in PPI. This generally never changes and the optimal resolution is 72 PPI. Making this resolution larger will not make the image any better, it will simply make the file larger. 

Print Resolution

Print resolution is measured in DPI. This equates to the number of dots of ink per square inch of an image that a printer will output. Therefore, for a 600 DPI print, the printer will place 600 dots of ink per square inch to fill the print area. 300 DPI is the standard high quality resolution, with some people providing as high as 600 DPI files. 

A lot of times screen resolution and print resolution are used interchangeably and this causes confusion for most. 

If you're planning to print a document, you need to ensure the file you are saving is at 300 DPI of the final print size, which sounds a lot more complicated than it actually is. 

So, using the example before, if we have 300 DPI and an image that is 300 px by 300 px, we can print it at 1" by 1" to achieve the 300 DPI. If we take the same image and increase the size to 2" by 2", we would then be decreasing the print resolution to 150 DPI. The larger we try to print the image, the more pixellated it becomes. 

Here is a 1" cinnamon bun at 300 DPI

Now here is the SAME photo at 2" without changing resolution and just increasing the image size 

Make it even BIGGER and the quality just gets worse

As you can see from the above photo, what was very clear in the 1" by 1" has become more and more blurry as you expand the photo. Now I also have this JPEG saved as 12x12 in 300 DPI and look at it there

Much clearer than the expanded image above, right? So you really just need to ensure you are saving your files in the appropriate SIZE and format file. 

If you have any additional questions feel free to ask below in the comments. Also, be sure to join my Facebook group as I do post most of my blog updates and file updates there as well. You can join by clicking the link!

Cheers
Tanya