Berth Posted January 30, 2014 Share #1 Posted January 30, 2014 Advertisement (gone after registration) I've noted the luminance histogram for all of my black & white images shows a very sharp spike on the right side (highlights?) of the histogram. Is that normal, or the sign of light leakage? Link to post Share on other sites More sharing options...
Advertisement Posted January 30, 2014 Posted January 30, 2014 Hi Berth, Take a look here MP histogram question. I'm sure you'll find what you were looking for!
Nick_S Posted January 30, 2014 Share #2 Posted January 30, 2014 I've noted the luminance histogram for all of my black & white images shows a very sharp spike on the right side (highlights?) of the histogram. Is that normal, or the sign of light leakage? Are you cropping very slightly to ensure that the clear film base is excluded from the histogram? Nick Link to post Share on other sites More sharing options...
250swb Posted January 30, 2014 Share #3 Posted January 30, 2014 Ditto above comment, but you'd see leakage anyway, it would appear as a light toned flare like artefact in the picture because light leaks are directional and localised. Steve Link to post Share on other sites More sharing options...
Berth Posted January 30, 2014 Author Share #4 Posted January 30, 2014 Are you cropping very slightly to ensure that the clear film base is excluded from the histogram? Nick No, I'm not doing anything other than looking at the histograms of the images scanned by the Lab. Is cropping a necessary part of the scanning process? EDIT: I do note that the spike on the color slide film I had processed and scanned is driven by the 'blue channel'. Of course that might be because those images were taken of the ocean shoreline. Dunno. I'll be doing my own scanning in the future, just not now. Link to post Share on other sites More sharing options...
wda Posted January 30, 2014 Share #5 Posted January 30, 2014 You should be able to see if any rebate is included in the scanned file. Link to post Share on other sites More sharing options...
Berth Posted January 30, 2014 Author Share #6 Posted January 30, 2014 You should be able to see if any rebate is included in the scanned file. Just to be clear in my mind, are you saying the problem lies with the scan, not the camera, or the connection between camera body & lens? Link to post Share on other sites More sharing options...
pop Posted January 30, 2014 Share #7 Posted January 30, 2014 Advertisement (gone after registration) Actually, we can not say without having a look at a sample.From your description we can deduce that part of the area scanned is clear (as bright as possible). This might be due to the border around the image being included within the scanned area, but we can't tell without seeing.A light leak, OTOH, presumably would brighten parts of your image without completely bleaching that part. So, all in all, the explanations given so far seem more likely than a light leak of your MP. Link to post Share on other sites More sharing options...
Berth Posted January 30, 2014 Author Share #8 Posted January 30, 2014 Thank you all for of your replies. I'm going to visit my 'local' (35 mile/56 kilometer distant) lab and ask them to rescan the film. They're a reputable business so I don't think there will be any problem. Link to post Share on other sites More sharing options...
rolfe_tessem Posted January 30, 2014 Share #9 Posted January 30, 2014 Before you make the drive, look at one of the scans. Is there a black border around the image? If so, the spike you are seeing is probably the film rebate that was included in the scan. It is not a "problem" -- in fact, most people prefer their scans done with a bit of rebate included. Link to post Share on other sites More sharing options...
Berth Posted January 30, 2014 Author Share #10 Posted January 30, 2014 Before you make the drive, look at one of the scans. Is there a black border around the image? If so, the spike you are seeing is probably the film rebate that was included in the scan. It is not a "problem" -- in fact, most people prefer their scans done with a bit of rebate included. I'm sorry, I have no idea of what you're talking about. Link to post Share on other sites More sharing options...
pop Posted January 30, 2014 Share #11 Posted January 30, 2014 The spike on the histogram which you mentioned in your first post may not be a defect. If the pictures look "normal" on the screen, then they probably are. Link to post Share on other sites More sharing options...
Berth Posted January 30, 2014 Author Share #12 Posted January 30, 2014 The spike on the histogram which you mentioned in your first post may not be a defect. If the pictures look "normal" on the screen, then they probably are. Actually, the pictures from the 1st two rolls were pretty awful, the black & white really awful, but my only view of them was from the scan, not a print. The third roll, which I had done as a high resolution scan, was much better. Since that roll was all taken on a misty/foggy morning though I could be misled. The spike is there in all of them. The possible explanation from knowledgeable responders here sounds plausible to me. I'm going to have the two black & white film strips rescanned. With optimism. Link to post Share on other sites More sharing options...
250swb Posted January 31, 2014 Share #13 Posted January 31, 2014 Actually, the pictures from the 1st two rolls were pretty awful, the black & white really awful, but my only view of them was from the scan, not a print. The third roll, which I had done as a high resolution scan, was much better. Since that roll was all taken on a misty/foggy morning though I could be misled. The spike is there in all of them. You will always need to do a fair bit of post processing with a scanned negative to get the tones you want because neither the scanner, or the scanner operator, know anything about the scene you photographed, they are just trying to get as much information in the scan as possible. In fact a flat boring scan is best of all because that will have all the information available. You shouldn't read the histogram from a scanned negative as you would digital. Digital is equating each point on the histogram with an actual point in the scene in front of you. A scanned negative is not recording a scene, it is recording the structure of the negative and the scene is within that information. It isn't unusual to see spikes of redundant information at each end of the histogram depending on the film used or exposure or development and the scanning. And it doesn't necessarily mean the information has been 'clipped'. Equally some films can show a steep spike at the highlight end but because of the nature of film it is not an abrupt cut off like digital and is one of the reasons to enjoy film. Steve Link to post Share on other sites More sharing options...
jdlaing Posted January 31, 2014 Share #14 Posted January 31, 2014 "You shouldn't read the histogram from a scanned negative as you would digital." I quickly learned that lesson. You are correct. Link to post Share on other sites More sharing options...
Berth Posted February 1, 2014 Author Share #15 Posted February 1, 2014 Thanks 250swb, I have a lot to learn, and some very good teachers here. Link to post Share on other sites More sharing options...
philipus Posted February 10, 2014 Share #16 Posted February 10, 2014 In fact a flat boring scan is best of all because that will have all the information available. (...) It isn't unusual to see spikes of redundant information at each end of the histogram depending on the film used or exposure or development and the scanning. And it doesn't necessarily mean the information has been 'clipped'. Excellent points by Steve. Those spikes are interesting but usually nothing to worry about in my experience. I often have spikes at one or both ends of the histogram straight out of Vuescan. Here are two images to illustrate a flat scan and what it might look like after a bit of post-processing (any flaws in the quality are a result of my own developing skills). cheers philip Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/221172-mp-histogram-question/?do=findComment&comment=2529479'>More sharing options...
too old to care Posted February 10, 2014 Share #17 Posted February 10, 2014 Until this thread came up I never looked at the histogram when I scanned an image. Instead, I just looked at the image, and as others have said, made sure all the detail was there by reducing contrast to prevent blowouts. Now the histogram is bothering me, because I cannot make sense of it. A couple of days ago I scanned a negative (snow scene) and looked at the histogram. The histogram looked bad due to the snow (spike on the right side), but the scan came out fine and printed ok both on my printer. The negative also printed well in the darkroom. Guess I will stick with the scanned image and forget about the histogram again. Wayne Link to post Share on other sites More sharing options...
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