Jamie Roberts Posted February 20, 2007 Share #61  Posted February 20, 2007 Advertisement (gone after registration) @ Tim--you're right; I've got cabin-fever here for sure! LOL!!  Yes, you could make the same adjustment in LR if you can make a selection (or it has Lens vignette tools), and then change the color in a wide RGB space.  The advantage to LAB though, is that you can mess with color without affecting luminance detail. The L is only luminance; the AB are only color.  So, for example, one classic strategy for getting rid of color noise is to blur the A B channels and sharpen the L. You essentially get rid of small color variations at the same time boosting luminance detail.  Of course, things like noise ninja take care of this for you  And in theory, anything you can do in LAB luminance you should be able to do in a layer set to Luminance. But there is no equivalent for the color channels.  But in practice, detail shifts in RGB or CMYK when you mess with color. In Lab it doesn't, so I like, for a multi-dimensional vignette, to deal with the problems separately.  That's all! If the RAW converter had a way of getting rid of the cyan shift *and* the vignette based on lens calculations, then you'd never need to do this! Link to post Share on other sites More sharing options...
LJL Posted February 20, 2007 Share #62  Posted February 20, 2007  Seriously, what are the advantages of doing it this way? It seems more complex and at screen res at least the results seem similar. My idea would be to de-vig the luminance to the same degree in LR on both the actual and the mask files, then go with Dave's method.  Any thoughts  Tim  ps alright I've never really understood Lab mode....  Tim, If I may jump in a bit.....the method you are suggesting will/should work. The one real advantage of doing this in Lab is that it really does allow the separation of the luminance issues, which impact the vignetting most, from the red shift-cyan drift issue which is really somewhat independent from the vignetting. The color shift issue is going to happen with the lenses and filters because of the angle that the light passes through the filter. It will be there with or without vignetting, which is caused by the light angle passing through the lens. Even though they are issues that happen to overlap in appearance, they are the result of two different types of light angle things, one effecting luminance, the other color. That is the best way that I can think to explain this and why a single correction for vignetting alone is not sufficient, in my thinking. Not sure it that helps or not....  LJ  P.S. And I DO agrre with you an Jono about "not getting out enough" if we have to spend that much time doing stuff in Lab Link to post Share on other sites More sharing options...
Jamie Roberts Posted February 20, 2007 Share #63  Posted February 20, 2007 Duh .. to answer my own question, all you would have to do is desaturate the cyan mask, and now you have an instant layer mask for selection! OK, looks like it's time for me to get busy on this project ... what shall we call it .... Project Pringle Fairy?  Sure--let's try one and see how it goes I'm not sure what you mean by just desaturating the cyan mask, but I'm sure it works!  If we get a good mask, then a good solution is much easier! Link to post Share on other sites More sharing options...
tashley Posted February 20, 2007 Share #64  Posted February 20, 2007 Thanks Chaps!  I had twigged that we have separate luminance and color issues, which is why I think I'll have a bash at the LR de-vigging method followed by the Dave method. I'll also try Jamie's Lab method, but I WILL THEN GET OUT MORE!  Truly I will  ;-)  Tim Link to post Share on other sites More sharing options...
finkaudio Posted February 20, 2007 Share #65  Posted February 20, 2007 Hi,  here is a version corrected with PanaTools and a different white balance. The coated glass gives some addtional cyan that I think should stay, as it is not coming from the lens. (My guess)    Best regards  Karl-Heinz Link to post Share on other sites More sharing options...
dhoelscher Posted February 20, 2007 Author Share #66 Â Posted February 20, 2007 OK ... just to start the collection, here's the DNG for a cyan mask for the Cosina/Voigtlander 12mm f/4.5 Heliar lens. Â This is shot at f/8.0; focus at infinity. Â YouSendIt - File Sharing Transfer Delivery - PC FTP Replacement Link to post Share on other sites More sharing options...
ChrisC Posted February 21, 2007 Share #67 Â Posted February 21, 2007 Advertisement (gone after registration) Tim - Pardon my delayed reply, but thank you for posting the requested images; self evidently they stirred a lot of interest. Â Jamie - Speaking as someone who neither gets out enough, or strays into the murky voodoo world of LAB, thank you for your contribution of alternative corrections to Tim's images. Â Threads in this forum can roll away at a rapid pace, and surely there has to be a better way of retaining valuable work processes than leaving them to the mercy of forum history and the search engine efficiency? How about a 'sticky' of these work-arounds, with a link to the entire thread, but not containing the entire thread within the 'sticky'? Having a terrible memory [and still waiting for my M8, so I am without hands-on experience] It would be great to have access to processes such as cyan drift corrections from the front page of the forum. Â ..................Chris Link to post Share on other sites More sharing options...
dhoelscher Posted February 21, 2007 Author Share #68 Â Posted February 21, 2007 Chris, Â When some of my current experiments are completed, I'll post a new summary of my findings along with Jamie's and others' contributions. Â I'll attach a PDF of the summary, so that everybody can download it - and maybe the forum admins will sticky that PDF, if it truly is of general interest and usefulness. Link to post Share on other sites More sharing options...
Jamie Roberts Posted February 21, 2007 Share #69 Â Posted February 21, 2007 David-- Â Do you have a good representative image or two to go with that 15 CV (filtered) shot? I don't have a filter for my CV 15, but I'm pretty close with an adjustment that should work pretty well. Â (BTW--I'm wondering how you filter yours--I've seen some pretty good workarounds, but you need a certain size IR cut filter that I don't have--yet). Link to post Share on other sites More sharing options...
ChrisC Posted February 21, 2007 Share #70 Â Posted February 21, 2007 When ......completed, I'll post a new summary of my findings along with Jamie's and others' contributions......I'll attach a PDF of the summary....... Â David - That will be greatly appreciated by many I'm sure. I look forward to the summary, thank you. Â ...................Chris Link to post Share on other sites More sharing options...
dhoelscher Posted February 21, 2007 Author Share #71 Â Posted February 21, 2007 David--Â Do you have a good representative image or two to go with that 15 CV (filtered) shot? ... (BTW--I'm wondering how you filter yours--I've seen some pretty good workarounds, but you need a certain size IR cut filter that I don't have--yet). Â Hi Jamie! Â The shots that I've posted were with the 12mm, not the 15mm, but don't despair, I have the CV 15mm as well (Guy is my lens lust muse). Â As you probably know, the 12mm takes a very cool CV accessory that allows you to mount a 77mm filter. I have a 77mm B+W 486 filter for that purpose. The CV 15mm doesn't have the removable hood like the 12mm Heliar, but a little electrical tape will allow this 77mm attachment to fit onto the 15mm with acceptable kludginess. Â When I get back into the USA, I'll give you some 15mm filtered shots - while I'm on the road, I can send you some unfiltered (hopefully more interesting) CV 15mm shots from the Bahamas .... Â Is that what you meant? Link to post Share on other sites More sharing options...
Jamie Roberts Posted February 21, 2007 Share #72 Â Posted February 21, 2007 Hey David-- Â D'oh! I just read CV 15 when you said CV 12! Doesn't matter; the correction will still work (but no wonder it looked a little odd on my CV15 shots!) Â What I need is some nice representative filtered shots from the CV 12 Unfiltered would be ok too, just to check the luminance shift (no cyan, right?). Â Thanks! I think I'm beginning to get a pretty reliable method here nailed down. Link to post Share on other sites More sharing options...
dhoelscher Posted February 22, 2007 Author Share #73 Â Posted February 22, 2007 Hey thanks, Jamie! Â That's very cool that you've got something cooking, 'cause I'm discovering that just doing my method kinda sucks .. Â For example, for night shots, it just doesn't work ... blare-ing red in the darkness, no less! Â I can give you a mask for the Leica 21mm f/2.8 and some filtered shots tomorrow. I didn't carry my 77mm 486 nor my 12mm Heliar to the Bahamas ... so that'll have to wait until I get back to Austin ... Link to post Share on other sites More sharing options...
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