Author Topic: Sharpness below 0 - could it be helpful?  (Read 5474 times)

a1ex

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Sharpness below 0 - could it be helpful?
« on: August 27, 2012, 06:25:45 PM »
Like title says.

Eddie Svard (discocalculi) just found the register that controls picture style sharpness. By setting this register to 0, I've noticed that sharpness becomes slightly lower than Canon's 0 level (as in Neutral 0,-4,-4,0). The effect is very slight, noticeable at 10x zoom on some fine texture, but it's definitely there.

Code: https://bitbucket.org/hudson/magic-lantern/changeset/e1ee35bfef54 - you can set the sharpness to -1 from Picture Style submenu.

Would this be helpful in any ways? Maybe masking moire or bitrate artifacts?

1%

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Re: Sharpness below 0 - could it be helpful?
« Reply #1 on: August 27, 2012, 06:29:05 PM »
Sounds helpful, the less sharpening the better. Can it go any lower?

a1ex

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Re: Sharpness below 0 - could it be helpful?
« Reply #2 on: August 27, 2012, 06:39:11 PM »
Writing 0 to that register seems the lowest it can go (and that's what you get when you set sharpness at -1 from menu).

If you write something to that register, picture style sharpness no longer has effect on the image, so it must be the register used by Canon code to set sharpness. I couldn't read the default value.

Sharpness value has to be shifted by 16. Range: 0 (lowest) - 0x1ff (highest). The highest value matches sharpness set at +7 from Canon menu.

Lowest byte seem to be doing something if you enable cartoon look (which is implemented as extreme sharpness): if set to FF the highlights are not sharpened, if set to 00, highlights are sharpened just like midtones. Couldn't notice any effect without cartoon look.

3pointedit

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Re: Sharpness below 0 - could it be helpful?
« Reply #3 on: August 28, 2012, 09:24:21 AM »
Are you saying that sharpness can be set based on luminance, or is that only available to cartoon effect?

Where does the sharpening occur in the image processing? Is that before line binning causing aliasing? I guess it could be better to eliminate more moire, but I doubt that many people really do turn it down that often.

Perhaops the effect is more noticable in the 5D III?
550D on ML-roids

a1ex

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Re: Sharpness below 0 - could it be helpful?
« Reply #4 on: August 28, 2012, 09:30:27 AM »
Sharpness is applied based on luminance, and thresholds can be probably controlled somewhat. With cartoon effect it's easier to see where sharpness is applied, because it's exaggerated.

It doesn't occur before line skipping, obviously. So it will not reduce moire, only mask it.

locoboy

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Re: Sharpness below 0 - could it be helpful?
« Reply #5 on: February 19, 2013, 08:04:49 PM »
i just tested it, with lightform picture style: -1 , -4 -,1 ,1  (magic hack) & add unsharp mask in post it seems to alow u to get bette "sharpe" image with out having the gosting effect whene u add the post sharpness !! need more tests !!

hjfilmspeed

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Re: Sharpness below 0 - could it be helpful?
« Reply #6 on: February 21, 2013, 11:54:17 PM »
Canons current method of sharpening in camera looks good on its still images. Probably because its radius is fine tune for higher megapixel/rez. It would be nice if we could fine tune the sharpness for video so theres no halos. then we could aviod sharpening the h.264 artifacts when we sharpen in post. I wish canon would add picture styles that were tuned for video too. i wonder if we will see canon log option on the 5d3 when they add the uncompressed hdmi rubbish. uggg the 5d3 is such love hate for me!