Being photographers, we are often privy to the word “Resize”. And it is often mentioned to resize a photograph to a particular dimension. So, resizing basically means converting a photograph from that dimension to a smaller dimension, without changing any of the visual aspects in it. In simple terms, resizing just means to reduce the pixels in the photographs.
Sony Alpha A 9 DSLR camera delivers a dimension of 6000*4000 px as it’s image dimension. A Canon 5D MK III delivers an image dimension of 5760*3840 pixels and multiplying 5760 by 3840, we get 22118400 pixels which in turn becomes 22.1 Megapixels.
Every photograph/digital image comes with a dimension. You can find the dimension of the photograph by right-clicking on the image and choosing “properties” as shown in the image below.
But the catch is, an image file having a dimension of 6000*4000 would be 240,00,000 pixels, in other words, 24 million pixels or 24 megapixels. Generally, this file(jpg) comes at a file size of 10~16 MB. And the file size varies based on parameters like exposure, colour values, compression/conversion algorithm and other finer details of the image.
Resizing plays a major role here as it would take a long time to transfer a file at the size of 10 MB and above. For digital display purposes and mail transfer purposes, you might need to resize the image to a size of 1600 px by 1066 px(aspect ratio 3:2) which in turn will directly reduce the file size to around 1 MB. You see the difference?
Converting from a larger dimension to smaller dimension without cropping or adding up anything to the image is called “resizing”. The result is that we get a smaller size file which helps us in transferring the files in a quicker manner.
You don’t need the full resolution photograph which is sized around 6000*4000 px or 5760*3840 pixels except when you want to use them for printing purposes.
Trust this post about resizing gives clarification about bringing down the size of a photograph and the direct relationship with the dimensions of the file and it’s size.