The More Resolution, The Larger The Potential Print Size
The image sensor of a camera also contains pixels. Those pixels gather information about the image you’re taking a photo of. They register what colors are visible and where the colors are located in the image. A “megapixel” is one million (1.000.000) pixels.
For example: A 24,2 megapixel camera has an image sensor with over 24 million pixels.
The more pixels on the sensor, the more pixels a photo contains, and the more detailed a photo is. It measures how big a image your camera can take. One thing the megapixel is not – a metric for quality of the image. More pixels just mean that you can stretch the image wider on a canvas without any noticeable distortion.
If you take a high-resolution photo, you can zoom in on the details. For images viewed on a computer monitor or a smartphone, this may not matter much but it has a huge impact on those that actually want to print their images out.
A disadvantage: your memory card will be full faster since high-resolution files are often large.
The purpose of the print determines the resolution that you need. Let’s say that you need to print a couple of your photos for family album. 5 x 7″ size is what you are looking for. These prints will be seen from a distance of about arm’s length. Which means a minimum resolution of 300 DPI is necessary.
Larger prints would require you to either drop the DPI to a lower number, or use special third party tools that use complex algorithms to upscale or “up-sample” an image to a higher resolution.
For example: Billboards are always viewed from large distances; 50″ or more. For printing these big you hardly need 15 – 40 DPI.
Example: I want print 16 x 20″ poster at 300 DPI:
(16 inches x 300 dpi) x (20 inches x 300dpi) / 1,000,000 = 4800 x 6000 / 1,000,000 = 28.8 MP
4800 x 6000 – pixels goal28.8 MP – MINIMUM DESIRED CAMERA MEGAPIXELS
This is a bit of a saviour for those of us trying to print a little bigger than our file’s resolution. Of course this isn’t fool proof, and blowing pictures up extra large will begin to look strange.
1. At the top of your screen, go to Image > Resize > Image Size.
2. Make sure Constrain Proportions and Resample Image are selected in the lower-left corner of the window.
3. In the menu at the bottom of the window, change Bicubic to Bicubic Smoother.
4. Highlight the width value, and enter the value you need. The value you use is the width (horizontal) value from the calcultor. The height value changes automatically when you enter a new width value.
5. Click OK.
For the highest quality images, make sure you are taking good photographs. Do not overlook capturing images in RAW. Or keeping your ISO low, using a fast lens. These will help your images a lot more than having high megapixel camera.