06-15-2011, 10:59 PM
[quote name='Brightcolours' timestamp='1308172389' post='9269']
No, NOT selective desaturation. Shrinking one of the colour channels, or expanding it, will not desaturate anything. Just make all 3 channels the same size again, which will mean the coloured edges will disappear, the CA induced sharpness will disappear and the contrast will recover.
You shrink or expand it from the image center.[/quote]
If you mean less desaturation in the centre and more towards the edges: that is what I mean by selective desaturation.
Well, let's just agree to disagree in that case. What [color="#ff0000"]you[/color] see is PF and some LoCa, what[color="#ff0000"] I[/color] see is PF, LoCa, and lateral CA. IOW, WE do not see the same things, IOW, don't use WE in this case unless you are of royal descent and head of state. I am not in the group with the same opinion here, so please don't say "we".
As I mentioned: not with Nikkor lenses, and as I mentioned, it was defined with yellow and blue; I was taught so about 35 years ago that CA was defined as yellow/blue artefacts.
Regards, Wim
P.S.: I am out of here, I don't have time for these discussions. As mentioned, I only wanted to add some hopefully useful info to this topic. You don't agree with me, but I didn't really expect anything else.
Cheerio.
No, NOT selective desaturation. Shrinking one of the colour channels, or expanding it, will not desaturate anything. Just make all 3 channels the same size again, which will mean the coloured edges will disappear, the CA induced sharpness will disappear and the contrast will recover.
You shrink or expand it from the image center.[/quote]
If you mean less desaturation in the centre and more towards the edges: that is what I mean by selective desaturation.
Quote:The one you think was not directed at you, that one is about desaturating of colours, which is the less desirable way.
About you not needing an explanation, what you wrote about the CA needed some correcting. There is no La CA to be seen, not the blue part of the spectrum of the nose at least. All that is just PF. CA would show a totally different, and directional, character. The upper part of the instrument, if it was CA, would show on one side, seen from the center of the image, blue, and on the other side yellow lines around the dark parts. On the sides that are not on the direction towards the center of there image there would be no CA.
That is just the nature of LaCA. What [color="#ff0000"]we[/color] see is PF and some LoCA.
Well, let's just agree to disagree in that case. What [color="#ff0000"]you[/color] see is PF and some LoCa, what[color="#ff0000"] I[/color] see is PF, LoCa, and lateral CA. IOW, WE do not see the same things, IOW, don't use WE in this case unless you are of royal descent and head of state. I am not in the group with the same opinion here, so please don't say "we".
Quote:The colour of CA needed further explanation too, as yellow/blue is quite rare.
As I mentioned: not with Nikkor lenses, and as I mentioned, it was defined with yellow and blue; I was taught so about 35 years ago that CA was defined as yellow/blue artefacts.
Quote:And yes, you are correct in understanding that with LaCA I am referring to Lateral Chromatic Aberration, as opposed to LoCA (longitudinal Chromatic Aberration)
Regards, Wim
P.S.: I am out of here, I don't have time for these discussions. As mentioned, I only wanted to add some hopefully useful info to this topic. You don't agree with me, but I didn't really expect anything else.
Cheerio.
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
