tom_halfhill Posted March 24, 2004 Share Posted March 24, 2004 For hours I've been trying to figure out how to use my new Epson 4870scanner. Maybe someone can help. Over the past two years I've scannedmore than 1,000 negatives and prints with my Epson 1640SU, but the"Professional Mode" exposure controls for the Epson 4870 arecompletely different and make no sense to me. See the attached screen shot. For a test, I tried scanning a 35mm b&wnegative that is normally exposed and developed. It's a full-rangenegative that makes a beautiful print in the darkroom onnormal-contrast paper. Yet when I scan it with the 4870, the Epsonhistogram shows the tonal scale extremely compressed. In fact, onlyabout half of the 8-bit tonal scale is captured. My Epson 1640SU had exposure controls for setting the shadow andhighlight values. By manipulating those values and scanning again, Iwas able to capture the whole tonal scale. (Not resampling or"stretching" the scale, as in Photoshop levels; I mean actuallychanging the exposure to scan more tones in the first place.) Eventhough the 1640SU scanning software didn't have a histogram display, Ibecame so adept at judging the preview image and adjusting theexposure that I was nearly always able to get a full tonal scale whenI opened the image in Photoshop. The 4870 scanning software now has a histogram display, unlike the1640SU, but the exposure controls are gone. I can't find a way toadjust the shadow and highlight points, rescan, and obtain a fulltonal scale. There are "brightness" and "contrast" controls, but theyonly seem to affect the preview image. Rescanning at the new settingsdoesn't enlarge the histogram. The eyedroppers on the histogram panel don't seem to affect thescanning exposure, either...they only change the preview image,usually for the worse. Moving the pointers on the histogram to theendpoints of the tonal scale and rescanning doesn't work. Changing theinput and output values doesn't work. All of these things affect theappearance of the preview image, but not the scanning exposure or thehistogram. The preview panel has a densitometer -- another new feature in the4870 -- but I can't figure out how that works, either. By moving ahand cursor over the preview image, I can view the tonal value ofindividual pixels in the image in the densitometer window, and thedensitometer shows "before" and "after" values for those pixels.According to the online help, those are the values before and after Imade my image adjustments. But something's wrong, because thedensitometer displays vastly different before-and-after values evenwhen I haven't made any adjustments and simply accepted the defaultsettings. Can anybody explain how the 4870's controls work? Is there any way toactually change the exposure of a scan? So far, I haven't been able tocome anywhere close to the quality of scans I easily obtained with the1640SU. Link to comment Share on other sites More sharing options...
tom_halfhill Posted March 24, 2004 Author Share Posted March 24, 2004 Here is a screen shot of the densitometer window, showing bogus "before" and "after" values for a pixel: Link to comment Share on other sites More sharing options...
johann_fuller Posted March 24, 2004 Share Posted March 24, 2004 Switch off all color control and scan with 48bit RGB - adjust the image in your image editor. Link to comment Share on other sites More sharing options...
gaetano catelli Posted March 24, 2004 Share Posted March 24, 2004 great questions, which i share, as owner of a new 4870. Link to comment Share on other sites More sharing options...
tom_halfhill Posted March 24, 2004 Author Share Posted March 24, 2004 Johann, Why scan b&w in 48-bit RGB? Do you mean 16-bit grayscale? I already tried that and it makes no difference in how the scanner controls work. Yes, I can adjust the image in Photoshop, but that's not a good solution, because the tonal range of the image is severely compressed. "Stretching" the histogram in Photoshop levels will create many gaps in the tonal scale, the so-called "picket-fence effect." What I'm trying to do is adjust the scanner to capture a full-range image to begin with. Link to comment Share on other sites More sharing options...
custom film holders for fl Posted March 24, 2004 Share Posted March 24, 2004 <body lang=EN-US link=blue vlink=purple style='tab-interval:.5in'> <p class=MsoNormal style='tab-stops:list .5in'>I just went in and tried similar changes.<span style="mso-spacerun: yes"> </span>Each time the changes were reflected in the preview (both zoom and normal) and in the resulting scan file.<span style="mso-spacerun: yes"> </span>Do you have the latest version of the drivers for this scanner?<span style="mso-spacerun: yes"> </span>Maybe this was fixed in the latest update (2.03A for U.S. users).<span style="mso-spacerun: yes"> </span>Just a thought�</p> <p class=MsoNormal style='tab-stops:list .5in'>Doug</p> <p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span style='font-size:10.0pt;mso-bidi-font-size:12.0pt'><a href="http://home.earthlink.net/~dougfisher/holder/mfholderintro.html">Doug�s �MF Film Holder� for batch scanning "strips" of 120/220 medium format film with flatbeds</a><o:p></o:p></span></p> <p class=MsoNormal><![if !supportEmptyParas]> <![endif]><o:p></o:p></p> </body> Link to comment Share on other sites More sharing options...
tom_halfhill Posted March 24, 2004 Author Share Posted March 24, 2004 Yes, I have installed the latest scanner driver (2.03A). The screen shot below shows what happens when I move the dark-point and light-point sliders inward to mark the ends of the compressed histogram, change the output points to 0 and 255 (for the widest possible tonal range), and refresh the preview image. As you can see, the histogram is still very compressed -- unchanged from the first screen shot I posted above -- and the preview image is still very flat, with compressed dynamic range. In other words, no manipulation of the controls has changed the scanner exposure. Also, notice the strange tonal curve at the bottom of the screen. The whole shadow region is flat and nonexistent. Link to comment Share on other sites More sharing options...
tom_halfhill Posted March 24, 2004 Author Share Posted March 24, 2004 When I scan the image with the compressed histogram -- after adjusting the endpoints and output levels as described above -- the image is still very flat when I open it in Photoshop. When I correct it with Auto Levels in Photoshop, I get the picket-fence effect, as shown in the Photoshop screen shot below. What I need is a way to adjust the scanner exposure to capture more tonal range. Otherwise, Photoshop doesn't have much to work with, and I'm throwing away dynamic range. Link to comment Share on other sites More sharing options...
leonard_evens Posted March 25, 2004 Share Posted March 25, 2004 I have an Epson 3200, and I haven't used the Epson software for it, so my comments may be irrelevant. But let me give it a try. Negatives have a lower density range than transparencies. The software may be treating the image as typical of reversal film and not taking into account the smaller density range. I assume you have the image source set as bw negative film, so the software should be able to figure out what to do, but apparently it isn't. It is certainly best to scan at 16 bits per channel and to get the RGB ranges right in the scan rather than doing it in Photoshop. It should be possible to do that. But don't get too excited about gaps in the histogram. You can get perfectly acceptable prints from such images. See Micahel Kieran's Photoshop Color Correction for a discussion of that issue. I use Vuescan, and I don't have such problems when scanning. You can get a trial version for free from www.hamrick.com. Link to comment Share on other sites More sharing options...
tom_halfhill Posted March 25, 2004 Author Share Posted March 25, 2004 Yes, I am scanning the b&w negative in b&w negative mode, not positive-transparency mode. And I have tried scanning the negative in both 8-bit and 16-bit grayscale modes; it makes no difference. Nor did I expect it to make a difference, because the histogram clearly shows that the scanner is finding only enough information in the negative for 6 or 7 bits of grayscale -- even an 8-bit scan is overkill for this negative. And that is strange, because it's a full-scale negative that prints beautifully in the darkroom. What I'm hoping to find is a way to adjust the scanner's exposure settings so it finds enough information in the negative to fill at least 8 bits, if not 16 bits. My old Epson 1640SU scanner was easily capable of making an 8-bit scan, even with negatives much worse than this one. Link to comment Share on other sites More sharing options...
steve_armstrong1 Posted March 26, 2004 Share Posted March 26, 2004 I'm glad you asked this question. I'm experiencing the same confusion with the Epson software for my 3200.<br> If I set the black and white sliders at the edges of the histogram when scanning colour negs and then bring the image into photoshop it is always underexposed. On the other hand, the automatic settings always seem to chop off the histogram (per your screen grab) which does not make sense. From my limited reading of scan technique I think it is better to expose the histogram to the right - I just cannot work out how to do this in the Epson software. Any ideas? Link to comment Share on other sites More sharing options...
steve_armstrong1 Posted March 26, 2004 Share Posted March 26, 2004 By the way, I have taken to using Vuescan instead of the Epson software as this has more obvious means of controlling scan brightness. The scans from Vuescan do seem to be a bit noisier however. Link to comment Share on other sites More sharing options...
michael_lewis8 Posted March 26, 2004 Share Posted March 26, 2004 Take a look at http://robertdfeinman.com/tips/tip11.html for how to get full range images from b&w negs. Link to comment Share on other sites More sharing options...
tom_halfhill Posted March 28, 2004 Author Share Posted March 28, 2004 Thanks for the tip. I will try scanning my b&w neg as a color transparency, then convert it to b&w in Photoshop as the web site recommends. When I tried that technique a few years ago with my old Epson 1640SU scanner, I couldn't see any difference when compared with b&w negs scanned normally. Maybe the new scanner will do better. Link to comment Share on other sites More sharing options...
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