Why do my photos turn out grainy and pixelated

Discussion in 'Digital Darkroom' started by deusnap, Jan 14, 2007.

  1. Hi, I'm currently using a Nikon D70 and as I have used it to take quite a number of shots in raw format, using ISO 200, my photos however turns out to be grainy and pixelated. Especially the blue skies in the photos. Is this a result of over processing in the digital sense? Many thanks!
    00JWa5-34435484.jpg
     
  2. I don't see it. The grain and pixels, that is. But then, I suppose you didn't upload a 100% crop. Do the look grainy and pixelated in print, or just on the monitor? What monitor are you using? Is it an LCD? What are you using for a RAW processor? Settings?
     
  3. Yes, you need to post a 100% crop... Also, try shooting the same scene in RAW and JPG. If the JPG is significantly less "grainy" than your RAW/NEF workflow is the problem.
     
  4. It looks by the example that you're shooting JPG and what I see is JPG compression artifacts. Try shooting in raw, or set your camera for the highest quality jpg setting. CLP
     
  5. it's cause you're shooting in the desert... of course it's gonna be grainy :) ...sorry, couldn't resist :p
     
  6. Sounds like dust on the sensor to me. Point the camera at a very light and evenly lit area, like the sky, and you will see spots. I hope that I am wrong. http://www.bythom.com/cleaning.htm
     
  7. If I look at your posted photo very closely, I can see some artifacts along the edges between the pyramids and the sky. It looks to me like a couple of problems - over processing and under-exposure.
     
  8. It looks underexposed to me, which will lead to grain. I'm guessing the jpg artifacting is due to the lo-res screen shot you're posting.
     
  9. Hello Chong. Your photo looks oversaturated to me. Have you added saturation during RAW conversion or later processing? Your camera contrast control is set to 2. I would suggest 0 and add contrast during processing - if necessary. If none of the above. Your camera was set to auto exposure so it's possible that it was confused by the difference between sky and pyramid and, as others have mentioned, the result is slight underexposure. Also, it is difficult to tell with this image but you do appear to have very slight dust on your sensor. Keep watching in case it gets worse. Geoff.
     
  10. Hi Chong, My .02 cents: You mention shooting in RAW but are you keeping them as 16-bit files while working on them? I don't convert to 8-bit jpeg unless necessary - posting to the web, etc. If it's not dust or under-exposure, you'll be surprised at how quickly an 8 bit file, (and all jpegs are 8-bit) with just a little manipulation, can start to fall apart - especially in "smooth" areas like blue sky. "16-bit" files can take much more manipulation without it showing and give much smoother tonal gradations. The downside? It'll eat up your storage space - but that gets cheaper every day. Good luck!
     
  11. If you used a polarizer for that shot, that could be a contributing factor in the blotchy sky colors.
     
  12. Hi guys, Many thanks for the response. I'm actually using Adobe Bridge for my raw workflow, and I'm working on a macbook. I've attached another photo, this time round in Adobe Bridge with the settings. And yeap I used a Polarizing Filter, but how does that contribute to the noise in the sky? If you look closely on the sky, top left expecially, you will notice the pixelation. Many thanks again!
    00JXFz-34444884.jpg
     
  13. Chong, What do you have loaded as your monitor profile? That last posted screenshot has an assigned generic ColorLCD profile which makes me suspect a display calibration/profile issue. That generic profile is the default profile Mac OS builds from info derived through the DDC of the display's ROM chip. It is the worst and most buggy default monitor profile in existance and can really create a crappy vLUT and cause all kinds of problems. I'm on Mac OS 9.2.2 and I trash this type of profile the first chance I get. I hope you calibrate with a puck based calibrator especially if using an LCD. Just want to take that out of the mix here.
     
  14. Unfortunately, I didn't calibrate my monitor and I've checked I'm indeed using color LCD. But What settings would you recommend without having to purchase a Spyder as it is quite pricy. Also, I didn't use any external LCD displays, just using my macbook screen. Thanks for the tip though.
     
  15. I suggest you first test to see if it is the generic LCD profile causing this by having Photoshop open while you access the Display Control panel and choose several different canned profiles. I don't know what profiles are included in OS X installs, but try to select anything that says Apple Standard, sRGB-(not the 2.1 working space), Apple Multisync D65, D50 etc., then immediately click back to PS to see if it changes-(not necessarily fixes) the artifacts in the image. Your image needs to be in a working space like AdobeRGB or some other one besides MonitorRGB. Check Working Space settings in Color Settings pref dialog box in PS to be sure. It the artifacts don't change then it's not the calibration causing it. Other than that it's best you calibrate your display with something other than canned profiles anyway if you want to edit digital color and expect reasonable matching print results. The best eyeball calibrator I've used on the Mac is SuperCal. Google it. At the time I used it, it was going for $20. Or try out the default Apple Calibrator. Things may have improved since OS 9.2.2. The main issue about eyeball calibrators will be choosing the right phosphor set because the wrong ones can make PS CM previews of peachy light tan fleshtones look intense coral and skyblue turn purplish and/or oversaturated. You'll have to try out different ones. Start with ones that say LCD. My Hitachi tube CRT has been very close to the sRGB space and those phosphor sets worked perfect. I can barely see a change to CM previews switching from my EyeOne to the SuperCal profile. The EyeOne, though, noticeably reduces banding in gradients on my 8 year old CRT. Good luck.
     
  16. les

    les

    Can you post a histogram of the RAW image ?
     
  17. Hi Tim, Many thanks for the suggestions, I've changed to sRGB as you have recommended. But the grains persist. I guess it might not be the cause of it though. But I will try with superCal as you recommended.
     
  18. Hi Leszek Scholz, the second image I posted has a histogram. Does that work for you?
     
  19. les

    les

    Well, the picture was shot at ISO200, f/8 and 1/500 sec - so it appears it should be well exposed (sunny 16 rule). Nonetheless, the applied corrections are: Brightness +100, Contrast +25, Exposure +0.35 - so my guess would be underexposure. The histogram looks OK (with the applied corrections), but it would be more educating to see it uncorrected - have a look if the histogram is bunched up to the left, if yes - then it is most likely underexposure. Funny as it sounds, underexposure happens frequently on sunny days, and it is really easy to overexpose a picture taken in the forest where the light is dim - it is just that the autoexposure system is not all that smart and tends to see everything as 18% gray. With a large portion of bright sky in the image - the camera may have the tendency to close down the aperture. My 2c.
     

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