is capture one 7 the only program that can correct lens color cast?

Hi
i gave a look to dxo 9 , lightroom v4 but i haven't found a feature that can correct lens color cast

i watched a video on youtube about capture one , and it's able to fix it
http://www.youtube.com​/watch?v=KBoSHz4kBKA


does somebody know if dxo pro or elite 9 , dxo view point 2 or acr/lightroom can correct color cast or capture one 7 is the only one?

thanks

Lightroom doesn't have anything specifically like that tool...if you do have a lens that causes a "color cast" then I suppose you'd want to mess with a sample image like their "neutral/clear" capture and mess with the white balance/colors until you get "neutral", and then make an LR preset for that particular lens...?

I know nothing about what dxo has!

Not a specific "tool", that I know of; but most of the editors will allow for white balance tweaks, it's just not a one click solution.

Snydremark wrote in post #16773437
Not a specific "tool", that I know of; but most of the editors will allow for white balance tweaks, it's just not a one click solution.

It is if you shoot a grey card.

The short answer to you question is "no." Lens color cast is not a white balance issue and can vary in color and exposure over the imaging field. White balancing will not correct this.

To use the LCC feature, you need to shoot an image under uniform illumination through a diffuse, translucent neutral material so that you get a map of the color and exposure issues caused exclusively by your lens. You feed this image to the LCC routine in C1 and it will compute the correction to neutralize the color and exposure across the imaging field.

You can also feed a high contrast (practically HDR) image to the LCC routine and then make a LCC out of it and apply it back to the original image to tone map the high contrast image. Nifty trick.

Kirk

Yeah, if I had a lens that had that problem, I guess the C1 tool would be good to have!

I use an xrite color checker to create a dual illuminant profile for my 7D. You can create a profile for every lens you own and use it in LR to correct color if the lens is causing color issues.

Titus213 wrote in post #16773865
I use an xrite color checker to create a dual illuminant profile for my 7D. You can create a profile for every lens you own and use it in LR to correct color if the lens is causing color issues.

^^^This will not correct a lens color cast either. The color cast is registered to the sensor field, not to a color target that you arbitrarily frame in the field.

watch the video to which the op linked to see an example of a highly egregious lens color cast.

None of the lenses I have ever used have this kind of cast, so I can imagine this is a rather specialized tool that may be more applicable to MF cameras and their optics or technical cameras and lenses.

What the heck would even cause that to happen, inherent to a lens; that looks seriously odd after watching the vid.

kirkt wrote in post #16773908
^^^This will not correct a lens color cast either. The color cast is registered to the sensor field, not to a color target that you arbitrarily frame in the field.

watch the video to which the op linked to see an example of a highly egregious lens color cast.

None of the lenses I have ever used have this kind of cast, so I can imagine this is a rather specialized tool that may be more applicable to MF cameras and their optics or technical cameras and lenses.

OK, so help me understand this. If I use a default profile generated for the lens with a color checker target the images of the color checker would include the color cast. Since the target is known values wouldn't the profile correct back to those colors too? No matter where the color cast came from?

http://www.phaseone.co​m …ticleid=2319&la​nguageid=1

older tutorial but steps through some LCC basics.

kirk

Here is C1's LCC tool being used to treat a high contrast scene:

http://help.phaseone.c​om …0Secret%20HDR%2​0Tool.aspx

I use Capture One's LCC for evening out illumination when shooting art reproductions, probably the the most practical use of it outside correcting color casts from wide angles on the A7r.

Lightroom does actually have a feature like this called "DNG flat field", but you download it as an add-on, and it's not as easy to use as C1's, probably they either don't have a high demand for it or still beta testing. http://labs.adobe.com …ads/lightroompl​ugins.html

Other than that, only Capture One does this because a good 90% of medium format backs you'll see on tech cams are either Phase or Leaf, both of which use C1 as their native Raw processor.

kirkt wrote in post #16774659
Here is a schematic example of why a lens color cast is not an issue that is correctable by WB or a custom DCP.

Say we have a lens that causes a color cast and vignetting as in this contrived example:

If we shoot a color checker target, this cast will be multiplied onto the image data like this:

What happens if we shoot the same color checker, but frame it slightly differently:

The color cast affects different colors in the target. In the end it really does not matter how you frame it because the DCP will give you a way to shift colors throughout the entire image, independent of location on the sensor. The lens color cast, as BigAl007 notes, is a pixel map of the way color varies across the imaging field (similarly, for exposure variation across the imaging field). DCP defines color shifts with respect to color anywhere in the imaging field.

If the color cast were like a filter across the lens, then WB or DCP may address the issue - the color cast would be the same at every pixel location.

The key to the LCC operation in C1 is that you shoot through a diffuse, translucent, neutral object that is backlit - this will produce a blurred image that will capture color and exposure variations across the imaging field caused by the optics between the translucent card and the sensor - the lens. The assumption is that this image should be perfectly uniform in color (neutral) and exposure - the LCC function generates a pixel map that produces this result from the input LCC image and then applies that pixel map to any image you would like to correct.

As I said previously, I have never found I have shot with a lens that required this level of correction.

kirk

Thanks -
I watched the video several times and never saw that the color cast was as you indicated. It's obvious to me now that a color checker wouldn't work.

I'd get rid of the lens.

Titus213 wrote in post #16775579
I'd get rid of the lens.

Probably sarcasm, but...

It's not so much a problem with the lens as the way light interacts with digital sensors, with film light could hit the surface at a 45° angle and still register detail with no color shifts, but now with sensor pixels and their narrow light-sensitive wells, an acute angle of incidence will cause purple/magenta/green/b​lue all over the place and it looks even worse than vignetting.

You'll never notice this with DSLRs because every lens has to "throw" the image circle past the mirror box, but in cameras where the lens can potentially press right up against the sensor surface you either need LCC correction or the lens needs to be a retro-focus design, substantially increasing it's weight, size, price, complexity and potentially reducing sharpness. Though, with especially large sensors and extreme lens shifts/tilts, a retro-focus lens needs to be used anyway.