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Content aware image resizing


Free image retouching alternatives to Photoshop


Beautiful picture, isn’t it?

Reflection of balloons on the river at sunrise — photo by Seattle Miles

Reflection of balloons on the Yakima river at sunrise ©Seattle Miles


You have a large picture, just like the one you see here above.
Say you need to make it narrower, about half its size.
Either you crop it, thus loosing left/right areas of the picture, or you resize it, making it visually more compressed.

Let’s see what happens in both cases.


Cropping

Reflection of balloons on the river at sunrise — photo by Seattle Miles

Cropped ©Seattle Miles

One of the most basic photo manipulation processes, cropping is the most immediate way to handle the issue: you can change the picture aspect ratio in a second.

We believe that cropping is definitely the best way to give a new life to some of your imagesand we have for you a dedicated page about cropping that you should visit one day.

Yet, in this case will loose a valuable part of our image: the fourth balloon at right, which we would like to keep.

Resizing

Reflection of balloons on the river at sunrise — photo by Seattle Miles

Overall squeezed ©Seattle Miles

Another typical approach is resizing, which means reducing the overall width (or height, or both) of the picture by squeezing all the pixels.

Standard resizing has advantages but:

  • some valuable details could be lost
  • some relevant subject could be distorted beyond a tolerable limit

In this very case, squeezing the trees would not be that much of an issue, but balloons and the house are far too slim and spoiled by resizing.

There should be another way to accomplish the task.
And yes, the solution is much simpler that one would expect: smart rescaling.


Smart scaling

Reflection of balloons on the river at sunrise — photo by Seattle Miles

Rescaled ©Seattle Miles

Smart scaling is a bit of a different concept.
Image resizing by seam carving (so it is also called, technically) avoids distortion of the important image parts while dropping and/or reducing empty spaces and zones where no real information is contained.

So, what happens in elastic resizing, intelligent rescaling or whatever it is called, is that relevant subjects (balloons, house) are automatically detected and kept the way the originally were, whereas not-so-critical subjects (water, trees) are squeezed.
This way we can combine the good of both worlds.
As a bouns, all is done automatically.

Sure, the last word on your own pictures is yours, also because there is not only technical information involved, but also an aesthetic value to be preserved and enhanced.

Now we will teach you how to.


How to resize a digital image the smart way

This video will show you how to rescale a photograph in order to stretch it or squeeze it without loosing its most relevant details (the lighthouse and the seagulls in this example). Look at the magic of it. You will notice that, should some odd distortion occur, you can protect the key elements by simply masking them. The image then rescales well, and you can reliably shrink or enlarge it as you see fit.


©Original photo of Lorain Lighthouse by Rona Proudfoot http://www.youtube.com/watch?v=BShFP8EQYU8%%

Advanced photo resizing by liquid rescaling
This video shows an advanced image resizing technique useful to greatly enhance digital images with little effort. Resizing is a key feature in any image editing software. But standard resizing method deforms key subjects along with the the whole picture. Here is where content aware image resizing software comes into play: see this demo and read more in-depth explanation at http://www.kirpi.it/. Smart scaling avoids distortion of the important parts of the photograph by gradually dropping empty spaces without interest first. Should some odd distortion occur, you can protect the key elements by simply masking them. The image then rescales well, and you can reliably shrink or enlarge it as you see fit. Of course, this demo does not reflect the actual image quality, which remains suitably high in real-life conditions. Learn more at http://www.kirpi.it


Of course, this demo video was created for teaching purposes and does not reflect the actual image quality, which remains suitably high in real-life conditions.
Also, right the same rescaling algorithm can be applied to the vertical axis of your image as well.


Look at the results

The lighthouse is still there, with all its details and shiny reflections. The seagulls as well are all there. None of them has been cropped or distorted in any way.
Yet the whole photo has been resized overall, successfully.
All was done in very short time, with a few clicks of the mouse and no advanced knowledge of imaging software.

Click on the images to see them bigger.

Lorain lighthouse and seagulls — photo by Rona Proudfoot

Lorain lighthouse — original ©Rona Proudfoot


Lorain lighthouse and seagulls — photo by Rona Proudfoot

Narrowed ©Rona Proudfoot


Lorain lighthouse and seagulls — photo by Rona Proudfoot

Widened — Lighthouse and seagulls are correctly rendered ©Rona Proudfoot



How can I try it myself?

There are many available tools you can choose from for image retargeting.
Some free choices we suggest for your first tests are:

All three software are working on Mac, Linux and Windows.

It is worth to underline here than in real life images one would often consider an approach which includes both traditional crop/resize techniques by means of a standard image editing software and liquid rescaling.


Last but not least

As you might have noticed, such smart resizing also supports manual selection and masking, which proves useful most of the time.
Interestingly, masking can also be used to remove portions of the picture in a consistent way. It is a both interesting and funny way to clean some of your pictures, which we suggest you to explore.




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