Photo Sharpening Tips You Need to Know
There are lots of tools and techniques you can adopt for sharpening your photos. But even then you can achieve widely differing results if you are not following good practice. This tutorial provides some helpful photo sharpening tips you need to know. Use these to ensure you make the most of your photos by sharpening them correctly.
Follow a Proven Sharpening Methodology
If we look back 10 years the commonly recommended “best advice” was that sharpening was something that you did as the final step of the image editing process. As with most things there is a grain of truth in this, but if you ae still following this advice your results will be sub-optimal.
The best approach to sharpening that I have found is the one described by the late Bruce Frazer in his book “Real World Sharpening”. In a nutshell he sets out that sharpening is a three stage process:
- Capture sharpening that’s intended to counter the softening effect of digital image capture. This should be done at the point of RAW conversion, before you begin serious image editing. This is often done as part of the RAW conversion but it can be performed immediately after, before you start making further image adjustments. The assumption here is that you will be shooting in RAW format. If you are shooting in JPEG, this sharpening is applied automatically by the sharpening settings in your camera.
- Creative Sharpening is part of the image editing process and is where image sharpening and blurring is applied to local areas of the photo (rather than globally). This technique is intended to help direct the viewer’s attention onto the most important aspects of the image and away from the less important. The best time to do this is usually when you have made all your adjustments and you are ready to output the image.
- Output sharpening is where you sharpen the image at a level appropriate to the output medium. If your image is to be printed, the level and technique used to sharpen will differ from an image that will be viewed on screen (see the later section on sharpening for output). Typically this form of sharpening is done as the final step. You certainly don’t want to be changing the size/resolution of the image once you have applied this final sharpening. Such changes will only result in a poorly sharpened image.
Don’t Sharpen Twice
Now don’t pull your hair out given the previous tip recommended you sharpen your image three times. What this tip is really saying is that you shouldn’t apply the same type of sharpening twice. For example, if you apply Capture sharpening in your RAW conversion, don’t apply a second pass of capture sharpening, especially if you mix the sharpening tools. Repeating sharpening steps in the workflow can easily result in images being overly sharpened, having obvious sharpening artefacts of simply having sub optimal sharpening.
Don’t Sharpen Noise
Once you start to sharpen noise it will become more visible in your images and probably detract from the finished image quality. Once you sharpen noise it becomes much more difficult to remove from the image. It’s therefore best to apply noise reduction before you apply sharpening. If you are shooting in RAW format and apply both noise reduction and sharpening as part of the RAW conversion then this will be taken care of for you. If you decide to apply these afterwards always do the noise reduction first.
Noise is not like film grain and will distract from the end result. Even film grain must be carefully sharpened so that it doesn’t become too harsh and affect the appeal of the image.
Sharpen for the Target Output
We have already mentioned this in the first section above but there is a little more you need to know.
- Screen Sharpening - If you intend your image to be viewed on a screen only you should resize the image to the final size/resolution. You should then zoom in to 100% magnification whilst you apply your sharpening in order to judge the correct amount and radius to use.
- Print output – Again you should resize your image before applying such sharpening. Here you will most likely need to view the image at 50% or possibly 25% resolution to judge the sharpening correctly. In reality you will need to sharpen and print the image in order to make further adjustments. The correct level of magnification to use will depend on your printer and screen combination. The best approach is actually to use the right tool for the job which is discussed in the next section.
If you’re thinking this potentially means you need two versions of the image if you intend to display it on screen and in print, then you’re right.
Use the Right Tool for the Job
Sharpening plug-ins (for example Nik Sharpener Pro) often have settings for print output. These determine the level of sharpening and the sharpening radius to apply based on a number of variables. This can definitely remove a lot of the guess work from the process and lead to much better results but you need to know how to correctly use them for the best results.
Lightroom too has a dedicated output sharpening section found I the Print Module. Whilst this isn’t as sophisticated as a tool such as Nik Sharpener Pro, it still produces a very good result.
If you're using Photoshop to sharpen your photos be sure to read my article Sharpening Photos with the Photoshop Unsharp Mask. You might also find the articles Edge Sharpening in Photoshop and Photoshop High Pass Sharpening helpful.