Resize and Sharpen for Web
Tutorials :3rd of July 2011
Sharpening your photos for the web is important if you want to display your photos at their best. Sharpening reveals details of an image more clearly and can give a professional finish to your images. The process used below is a more advanced web sharpening method that produces, in my opinion, the best results possible. It's a largely automated resize and sharpen process, but the results are outstanding and should give you web images that little bit extra.
An example of Web Sharpening:
Obviously both sharpened versions are considerably better than the unsharpened web image. A more worthwhile comparison comes when comparing the basic Unsharp Mask (USM) application and the advanced method. In short the benefits are as follows:
- The details are finer and cleaner, USM seems a little ‘muddy’ in comparison. The shadow details are more noticeable
- The colour is fractionally better
- Selective sharpening has been used to remove halos on the horizon
Overall the differences between the images are small but tangible. The advanced web sharpening method gives the web image that finishing touch that can make all the difference. Even side by side the differences are small (I'm not attempting to fake the reults here!) but these improvements are consistent across all images and in images with significant fine shadow detail the improvement is more significant.
Download the Advanced Sharpening For Web action set
Of course when you are outputting your photos for the web the last thing you want is to do is go through some complex sharpening process. For that reason I have produced an action set for free download! The Advanced Sharpening For Web action set was produced in Photoshop CS3 but it does seem to be compatible with other versions of Photoshop and certainly later versions! Unfortunately it does not work with foreign versions of Photoshop due to the file renaming.
Download: Advances Resize and Sharpen for Web
How to use the action set to sharpen your images
Using the action set on a basic level should be very easy.
- Open your full size image.
- Save a copy of it if you want to make sure that you don’t overwrite the image with a small web resolution version (and yes I have done this several times!)
- Open the action palette and select the output image size you wish for you image (Note that the predefined sizes are split into width and height categories)
- Press ‘play’ to launch the action. You image should now be resized and sharpened
- If your image is over sharpened then reduce the visibility of the sharpening layers to taste.
- Finally flatten the image and ‘Save for web’ (I suggest a jpeg compression level of 60-75% for fast loading with acceptable compression levels)
If you want to get the very best out of your image then you should consider sharpening different areas of the image by different amounts. This can be achieved by painting on the layer masks. This isn’t the place to talk about layer masks in depth so hopefully you already know what they are and how to use them! When it comes to deciding which areas to sharpen more or less I would suggest you:
- Remove/reduce halos around high contrast edges
- Remove/reduce the appearance of artifacting or textures that shouldn’t be there
- Remove sharpening on areas that should be smooth such as skies
- Increase sharpening on areas that still aren’t well defined. I will often increase the sharpening on water and cloud details for example.
How it works
I can’t really tell you how it works but rather explain the process! Here is a step-by-step of how the sharpen for web action works (roughly and not ordered in exactly the same way as the action!) if you want to get into the real nitty gritty then have a look ‘inside’ the action!
- The image is resized to 1.66 times the desired output size. This is a critical step, for some reason 1.66 seems to work better than any other ratio!
- The image is duplicated and sharpened
- The sharpened image is duplicated and sharpened!
- The image is resized to its final output size
- A layer mask is applied to the sharpened layer
- A layer mask is applied to the double sharpened layer. This layer mask is made mid grey to effectively reduce its opacity to 50%
- The sharpened layers are set to luminosity mode to reduce/remove any colour changes introduced by the sharpening process.
- The colour space is changed to RGB to ensure that the colours display correctly on the web.
How to create new sizes
You may find that the size that you like to output to is not available. In that case you may need to modify the action set to create a new size option.
- Click on the web resize folder in the actions palette
- Click on the new action icon at the bottom of the layer palette
- Give your action a name (I suggest following the naming convention)
- Click Record
- Play the action 'Part 1 -ignore' on the actions palette
- Resize the image to 1.66 times your output size. For example if you want you image to finish 100px wide then click image>image size (set to bicubic) and set the size to 166px wide
- Play the action 'Part 1 -ignore' on the actions palette
- Resize the image to your desired output size. So for the example above that would be 100px wide.
Who came up with the idea?
The idea is not my own, but I have certainly adapted it quite a bit. I believe a similar method was made well known by Marc Adamus, but the specific ratio of 1.66 is the idea of another photographer whose name I can’t remember (it was a long time ago!). Since reading about the method I developed it based on my experience using it and feedback from other photographers on the best process. I won’t take any credit at all for the idea, but hopefully the action set is appreciated!
The action set is free but I am keen to share it with other photographers. If you have downloaded the action it would be great if you could link back to this page to help other people find it!
Sharpening for print.
This method can’t really be used to sharpen images for print. If that is your goal I personally recommend the use of the unsharp mask (USM) and smart sharpen filters. Although many articles on the internet and in books recommend sharpening an image taking into account print size and viewing distance I personally recommend that you sharpen your images to make the most of fine details. In my opinion it is far better to sharpen your images for print so that they look highly detailed on close inspection, and don’t display halos. For that reason you should use a sharpening radius of less than 2 although usually a radius of 1 or lower is best!