I would like to fix the problem on the bright area in the image below. I just want to make it white.. but I really don't know how to do.
When, I play with the Levels(), I notice that these pink areas remain stable.. I can darken or whiten the image completely, these areas (and only them) will always remain pink.
Also, is there a way to fix these annoying 'waves' on the film..
Here is a sample to download : http://www.mediafire.com/?47bz11g1hf28y30
Thank you in advance for any advices
+ Reply to Thread
Results 1 to 10 of 10
Something like this maybe:
mask=ColorYUV(off_y=-200).ColorYUV(gain_y=20000) Overlay(last, ColorYUV(last,cont_u=-256, cont_v=-256), 0, 0, mask)
Or maybe a mask built from the U channel (U is very high where the purple colors are), or both Y and U. Or try a chroma key.
Chroma based mask:
Last edited by jagabo; 30th Oct 2012 at 16:52.
The weird thing is that this purple area SHOULD be the brightest part.. but because of oversaturation, it becomes finally less bright than the rest. Is it due to a wrong YUV<->RGB convertion?
As a result, your script will paint in grey the purple areas which is not so nice..
I tried to reduce the saturation for the light areas in Color Mill and the result is not so bad.. at least no limits are visible like with the use of a mask.
But well.. I was hoping we could do better regarding this problem
Last edited by mathmax; 1st Nov 2012 at 05:55.
-Caused by the lens originally
I get purple halos even in my modern digital camera. One explanation is chromatic abberation, where some colors of light are bent differently than others leaving haloes, especially at the edges of the lens. That doesn't seem the case here.
-Caused by the camera originally
The other reason is sensor saturation; maybe the green channels are clipped while the other channels are close to clipping, leaving a purplish colour.
It could be that due to the white balance of the camera, the raw green values were relatively boosted.
It can also come from non-linearity of the ADC near saturation which does happen, but that only applies to modern cameras.
If this is old footage, then a whole other set of camera artefacts apply from tube cameras. I'm not as familiar with these.
-Caused by VHS
Finally it could be an effect of VHS, but I don't know the reason.
To fix it, I'd try some techniques from re-colouring, like the colorit filters. They can be used to do a type of flood fill or to selectively replace all purple colours with white.
As for the wavy lines, you need vcmohamn's fan filter plugin, it's made just for this. (fan refers to the interference caused by a fan motor on a VHS on the same electrical branch circuit)
Last edited by jmac698; 19th Nov 2012 at 11:28.
The pink flare is from a pink spotlight. You can see it's aimed at Michael and is directed onto the stage floor (pink circle in lower right). It's not supposed to be white. You can see the same or similar pink spot shining on the floor in the bottom image of post #1.
Last edited by sanlyn; 19th Nov 2012 at 13:38.Our inventions are wont to be pretty toys, which distract our attention from serious things. They are but improved means to an unimproved end. -- Henry David Thoreau
my gut feeling tells me it's a chroma key issue (seeing that there is a label in the middle of the frame...)
old school chroma keyer... so 80's