LCD Discrepancy?

April 12, 2005 1:20 PM

When taking photos with my digital camera (Canon Powershot A75) images often look great on the LCD and then not-so-great when I actually get them onto my computer. Most notably, when taking B&W photos in relatively low-light they will look fantastic on the LCD and then just BLACK on my computer. I can usually make the image sort-of useable by photoshoping the levels, but then it gets real grainy. Is there anything that I can do to get a more accurate preview from the LCD or do I just have to accept the fact that it lies? Tips on dealing with this?

If it matters, I'm shooting at the highest resolution (2048x1546) and with Super-Fine quality.

posted by TurkishGolds to sports, hobbies, & recreation (14 comments total)

Are you viewing the pictures on a CRT or LCD monitor? I ask because the contrast and brightness levels differ and you might need a different monitor color profile. If you're using the image online, there might be some sort of levels/color correction for this type of thing that someone else may know.
posted by mikeh at 1:24 PM on April 12, 2005

viewing the images on both CRT and LCD produces about the same results.

The image looks great and cool on the camera LCD and then just looks like nothing but BLACK on the computer monitor.
posted by TurkishGolds at 1:29 PM on April 12, 2005

I don't have this specific camera, but I do have a Canon and I noticed the same problem. The best way to determine the actual levels of an image is to switch your display to show the histogram. When I'm taking photos of a subject using manual settings I usually take a test shot and then switch to the review mode to check the histogram. If the levels are in the mid range then I know everything is good. If the levels are skewed too light or dark then I go back and adjust my manual settings.

The LCD is just a preview. The actual image info is in the histogram. Hint: this is exactly the same for working on images within photoshop. Your monitor lies. The histogram does not.
posted by quadog at 1:34 PM on April 12, 2005

Sorry to hijack the thread but it's related - does anyone know of a detailed manual-how-to of the best way to use the manual mode on the Poweshot A75? I'm scared to use it.. mostly cause I don't know what I'm doing it. The manual describes what each thing does, but not how to use the settings to get excellent pictures.
posted by TuxHeDoh at 1:55 PM on April 12, 2005

I'd try two things in any situmatation like this, assuming you're not doing so already.

First, take the pictures as color and drop them to black and white on your desktop, not the camera. Then if you want you'll be able to tweak the levels of R, G, B going into the final product, and your big stonking computer will probably do a better job on the math of the conversion than your little wussy camera CPU will.

Second, take the pictures in raw if you can. In jpeg, you're only going to have 256 levels of grey to play with. In raw, at least 4 times as many (if it does 10-bit) or more probably 16 (for 12-bit) times as many.

Dunno if it'll help with the problem itself, but it should help get better b/w pictures out of the camera.
posted by ROU_Xenophobe at 2:00 PM on April 12, 2005

Are you able to change the LCD display on the camera to more accurately depict the actual photo? I have a new Fuji and am able to adjust the brightness of the LCD; I've assumed I need to be careful doing that as it will skew my perception of the actual photo.
posted by suchatreat at 2:15 PM on April 12, 2005

My guess is that you need to turn down the brightness of the camera LCD. Learning how to read a histogram and/or how to set exposure for a given scene may also be helpful.
posted by kindall at 2:24 PM on April 12, 2005

TuxHeDo - manual setting uses the same principles of aperture and shutter speed as apply in photography on film (or whatever medium). I don't have a specific book or website to recommend (aside from Ansel Adams The Camera if you are really hardcore), but pretty much any resource on the basic principles of photograpny can teach you about that. The basic idea is that, to create an image, light has to get to the film/CCD and the amount of light that reaches it is determined by the triangle between (a) how much light is bouncing off the subject, (b) how large is the aperture (the hole the light goes through), and (c) how long the shutter (which covers and reveals the hole) is open for. Managing that triangle is a combination of both art and science, but once you learn these principles the meaning of the histogram will open up to you and you'll have a big leg up on the science part. The art part is up to you.
posted by matildaben at 3:25 PM on April 12, 2005

Are you viewing the images on windows PCs only? My camera's LCD has great brightness, gamma, and is quite forgiving towards under exposure, as is my mac, but my PC when I had a cheap graphics card, old CRT, and badly tuned settings showed everything but the most perfect exposed photos as totally dark.

Getting the latest graphics card drivers and doing some calibration fixed things for me (and getting a new monitor and graphics card soon after also helped). My mac is still more forgiving towards underexposure, but not by much.
posted by mathowie at 3:26 PM on April 12, 2005

DO NOT EVER USE THE B&W MODE OF YOUR CAMERA. There is zero point to this, and even in the best of cases, you'll get just a straight desaturation, which is unlikely to be what you actually want. There are a number of good techniques for turning color images into black and white using photoshop, and if you preserve the original color image, you can do it differently later if you change your mind.
posted by Caviar at 3:30 PM on April 12, 2005

The histogram view will help you understand what's going on. Two other ideas.. Be sure you're doing the right gamma calibration, like mathowie said. And how does the photo look when you shrink it tiny on your computer screen, to the same physical size as the camera LCD?
posted by Nelson at 3:30 PM on April 12, 2005

There's no raw mode on the A75.

TurkishGolds: Are you using the monitor to guestimate exposure setting in manual mode under low light? The camera's meter works pretty well on its own to prevent gross underexposures in P, Av, or Tv modes, so there's no reason the pictures should be "almost black" unless you're exposing in full manual. In which case, you'd need to tweak your exposure settings accordingly against the histogram (NOT the screen) which is brought up under playback mode, DISP button. [Screenshots] Just in case you need it, here's a tutorial on reading and using histograms.

Remember that your camera's LCD screen is a light source, especially under dark conditions -- a "pitch black" 0 value on the LCD screen will still be illuminated in the darkness. Histograms don't suffer from the subjective perceptual issues when it comes to ambient light. Read and trust the histogram.

On an unrelated note, does it only underexpose in B&W or in color as well? It's better to just shoot color and deal with turning it into B&W later.

TuxHeDoh: You don't need to use full manual to get "excellent pictures." You'll know you need manual when you're cursing at the camera because you want to override something, usually related to metering. Av (aperture priority) and Tv (shutter speed priority) (or even program mode, P) is all that you'll likely need -- use P for "point and shoot", use Av to open your aperture as large as it goes (i.e. smaller f-stop numbers) when taking portraits or under dark lighting, and Tv with a high shutter speed when you need to freeze motion on a sunny day (or to set a long shutter speed for tripod work when it gets dark). Using full manual routinely is actually counterproductive if you're not absolutely confident of your metering and with setting your own exposures, since compact digital cameras have poor exposure latitude and are thus extremely unforgiving of faults in exposures. It will take a good dose of techique and/or trial-and-error on a single shot to get good results in manual mode, and it's not a generic way to get "excellent pictures." Are you trying to capture traffic/star trails or something?
posted by DaShiv at 3:33 PM on April 12, 2005

Try changing the ISO on the camera. If there's something awry in the electronics, perhaps it's not charging the CCD up high enough in BW mode. Also, I assume you're in manual mode to do BW - make sure you don't also have a -1 or -2 exposure set. I've noticed that both my Elph and my Digital Rebel show great exposures on the LCD even when the data is actually dim or blown out.
posted by notsnot at 9:50 PM on April 12, 2005

learn photoshop. increase brightness, lightness, and contrast levels and to your liking. the data is there, you've just gotta get to it.
posted by trinarian at 3:27 AM on April 13, 2005