# Sharpening 5D Mk III - red problem and solution



## JasonATL (May 17, 2012)

It is well known that video from the 5D3 benefits from sharpening. However, I was noticing some rather unattractive artifacts when sharpening shots with red in them. The red would pixelate or "ring" at the borders with other colors.

The solution I've found (that others might already know about) is to use a chroma blur filter prior to sharpening.

The frame grabs below show what is going on. You can check out my short video about this, if you're interested. Any comments or other tips to deal with this are appreciated.

https://vimeo.com/42314148


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## JasonATL (May 17, 2012)

Here's a shot at normal resolution, which shows that the artifacts are visible, even without zooming in.


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## Axilrod (May 18, 2012)

Man it's very hard to tell the difference between those. Are the supposed artifacts on top and bottom of the label or on the left and right?

You can only really sharpen the footage a very minimal amount, artificial sharpening can make any image look like crap if turn it up too far. As you slide your sharpness upward, wait until it starts to look bad and then back it down a bit. But it's not going to go very high before it starts to look bad, generally (on a scale of 0-100) I can get the sharpness to maybe about 4 or 5, but anything more than that just looks like crap. That's just how it is man. However if you shoot with the right glass/lighting you can get great looking video without any sharpness added.


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## JasonATL (May 18, 2012)

Axilrod said:


> Man it's very hard to tell the difference between those. Are the supposed artifacts on top and bottom of the label or on the left and right?



I agree, especially on the Vimeo video. But it is clear on my full resolution previews from my NLE timeline. Look at the 200% zoom screen capture at full resolution (i.e., open the attachment and view at 100%). It is all over the label on the far left, to a lesser extent on the unsharpened footage second to left, and not an issue on sharpened and chrom blurred shot on the far right. Look at the label wherever the red borders another color. 



> You can only really sharpen the footage a very minimal amount, artificial sharpening can make any image look like crap if turn it up too far.



Agreed. Although, if you watch the video, do you think I've sharpened too much? This is actually sharpened a bit more than I NORMALLY do, but not more than I've EVER done - and I understand well the points you make that too much sharpening can give a video a, well, video look. Thus, I'm generally conservative with my sharpening, which is why I didn't like the effect it had on red. 

My point isn't about sharpening in general. It is about sharpening with red objects. I think you'll find wide agreement that sharpening, in general, is beneficial to 5D3 footage -- I don't think I'm out on a limb on this one. As I said in the video, ANY amount of sharpening that I would add with a shot with red in it would reveal these artifacts of the red object.

I'm not claiming any dificiency in 5D3 footage. Indeed, the chroma blur trick probably is as effective on any other footage for which this issue arises. I would say, if you don't find this to be an issue in your footage, then ignore the chroma blur trick. For those that do, I offer this tip that I've found to work for me.


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## Axilrod (May 20, 2012)

Yeah I agree, it definitely does benefit from a bit of sharpening, and I wouldn't say it looks over sharpened. But there may be areas of the image that aren't responding as well to the sharpening, effectively over sharpening parts of it while the rest of it looks just fine.. I'm not sure what's causing the specific issue with the reds, but I'll check out some footage and see if I'm getting similar issues.


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