Resize, crop and canvas size: the most important image editing concepts you need to understand

Everyone heard about Adobe Photosop, the most used image editing software, but not everybody knows how to use it, that’s because we are talking about a complex software program and that’s enough to get people scared and not willing to give it a try. What people don’t know is that image editing has a lot of concepts that are common throughout various image editing solutions.

The Photoshop tool bar

It’s enough to know and understand a few image editing concepts and you can edit your own images for your blog. Today I’m gonna try and explain to you three concepts that will help you get a right sized image for your posts.

Resize

On yout computer screen image dimensions are expressed in pixels or px (small individual sqares, each of a special color). Let’s suppose your blog has a text column 400 pixels wide and you want to put a picture in a post that’s 1200 px wide. Your WordPress blog can resize it for you and link to the bigger image, but that ain’t gonna look good plus it will take more space on your precious hosting server.

What happens when you use a resize tool? In the example above each three pixels of the original image are squized into a single pixel and the color il calculated as a mean of the three initial pixels. If you get the options of resizing the image using a resample algoritm (look for this option in the Resize tool you use) you better check it as the resized image will look better. Also remember to keep the aspect ratio if you don’t want the resulting image to look distorted.

A smaller image will also have the advantage of occupying less space, if the resize length and width are smaller than the original size of the image.

Crop

This is a slightly different concept that will also make your resulting image smaller. A crop tool will allow you to select a portion of the image and crop to that selection (resulting image will contain only the pixels inside the selection). This is an useful tool when the initial image contains things you’re not interested in. If your tool has the option of specifying a size (width and height) for the crop area and you set those value the program you’re using will crop the pixels in the selection you provide and then apply a resize algorithm to the dimensions you specify (you got it, this is a two step operation).

Crop doesn’t have to be proportional and the resulting image won’t be distorted.

Canvas size

I’ve left this concept at the end as it’s a little bit more complicated to explain. Imagine you have a picture, 100 x 100 pixels, and you need more space in the left side to put some text there. By using the Canvas size tool you’ll be able to extend the working area of the picture in any direction by any size you want. The additional space will be filled with a color you choose in the tool’s options. In the resulting space, if you’ve increased it you’ll find all the graphic contents of the original picture.

Canvas tools also can be used to decrease the working area of the picture, but be careful, all information outside the resulting working area is lost. Decreasing canvas size is usually used when you want to eliminate unused space in an image and keep the rest of the pixels untouched.

That’s it for now. If you want to read about other image edition functions please state their names in the comment form below and I’ll try and explain them in future posts.