Noise / Grain issues and some print questions...

paulpippin29 · Jun 26, 2009

Hi all... couple of questions here.

My camera, which is a Canon Rebel XSI has a maximum resolution of 4272 X 2842 in the horizontal orientation, and 2848 X 4272 in the verical orientation. When I view images at these resolutions, having NOT resized them at all... I see alot of "grain"... and I don't want to call it noise, cause I've seen noise related to high iso shots, etc.. and it just doesn't look the same.

Now, I shoot in Manual mode at all times, RAW all the way. The camera is set to do nothing to the images... no in-camera editing is applied at all. I do any and all corrections / enhancments with PSE 7, mainly using ACR, then saving down to the highest quality JPEG that PS allows for when I'm finished.

Once I resize the images, the grain goes away, completly, so does that mean that the grain is simply from the large resolution of the image? Is it my crappy kit lense (I'm sure it doesn't help any) or is it something to do with the camera itself? How can I prevent it, or can I not? I shoot at the lowest possible ISO, which normally, I'm shooting outside with natural daylight, so my ISO is at 100, which is as low as the XSI will go.

Second question concerns printing...

In theory, if I ever start to get paid for my photography, part of my buisness plan, or sales pitch, whichever you might call it... is to give the customer a series of CD's, which would contain original images, fully edited and converted down to JPG for their own personal use. They can go anywhere they wish and have them printed. Now, I'm sure I"m not the first to do that, but my question is this...

I don't want them to load those images up and see that grain. If I were to do things the way I planned, would it be best to resize the images beforehand, or give them the original resolution. If they have the large resolution images, would that not enable them to print "poster" size photo's if they wanted to? In fact, would it be the case that the larger the original image to be printed, the better quality print you'de recieve? I guess the best way to sum this up is into one question... what is the optimum resolution for standard print sizes... 4x6, 8x10, etc... And if I don't resize the images, and allow the grain to stay, would it show up on the printed photo?

I'm clueless to printing, so forgive me for that. Ok, that's it, sorry for the long post as always, and thanks for reading and advising

Oh, I was gonna post an example that I took today, but when I uploaded it to Photobucket, it downsized the image to 1 meg in size, which also go rid of the grain, so I figured it was pointless.

Ok paulk... here's the example ( I didn't even think about cropping initially)

This was just a test shot of a flower in my back yard, and you can really see the grain in the flower petal.

paulk_68 · Jun 26, 2009

Blow the image up to 100% and crop an area without filling in any crop measurements about 640px by 480px in size (you will have to guess on the size), and then try loading it to Photobucket so you can post it here.

paulk_68 · Jun 26, 2009

Paulpippin29, this is only a guess but, I would say that it is noise caused by underexposure. Did you try to increase the exposure while post processing? While this is not a cure for the problem, you can try running your pictures through Noise Ninja or Neat Image like I did with the cropped image you posted here.

I used the Neat Image Home+ edition.

paulpippin29 · Jun 26, 2009

Wow... big improvment you made there.

Hmm... the underexposure possibility presents yet another delima of mine, one that I've discussed on here before, and one that still baffles me.

According to the camera, the picture is perfectly exposed. With this particular picture, there was nothing like a sky, or other bright or dark object that I needed to expose for, just the flower, and the green stems (or whatever they're called) Also, I should note that ACR did NOT opt to increase nor decrease my exposure on this image. It typically finds something wrong with my exposure, as it's always either a tad bit over or underexposed according to the software, and it adjust the issue on it's own.

Jeez... if exposure is indeed causing this, I need to just give up! lol... I've tried everything I can think of to properly expose, and I do it by the numbers, as taught how to here on the forum.

I'm off to check out this Neat Image Home Edition. I take it that Photoshop's noise reduction must not be as good?

paulk_68 · Jun 26, 2009

paulpippin29 said:
I'm off to check out this Neat Image Home Edition. I take it that Photoshop's noise reduction must not be as good?

The same can be done with Photoshop if you play around with the noise filters advanced settings. I like Neat Image because it took about 30 seconds to do what I did with your image, and you can batch edit up to 50 images with the edition I have.

Can you do a print screen of the histogram from that image and post it here?

Bitter Jeweler · Jun 26, 2009

PaulK_68, thanks for the Neat Image tip. I just downloaded it and gave it a try. Nicer job than what I was getting in photoshop. :thumbup:

musicaleCA · Jun 27, 2009

Yes, noise shows up on prints...that said, as I also have a 450D, I feel qualified to say this: ISO 100 is very clean. I've shot 4-minute exposures with it at 100 and had to only apply a minor amount of noise reduction. This leads me to believe that it's probably noise due to underexposure. Try to expose as far right on the histogram as possible without clipping any of the colour channels. As you move lower in the dynamic range of the camera sensor, there's more noise, and there's less information per pixel as well, relatively speaking. It's easy to turn down exposure in post and get fantastic results as long as you didn't clip anything. You're bound to add more noise to the image (and bring back less detail overall) when you're pumping up exposure in post.

Oh, and yes, it's called noise. Grain is the similar thing that happens to film.

paulk_68 · Jun 27, 2009

Bitter Jeweler said:
PaulK_68, thanks for the Neat Image tip. I just downloaded it and gave it a try. Nicer job than what I was getting in photoshop. :thumbup:

Cool, I'm glad if I was of some help

KmH · Jun 27, 2009

Unfortunately, if you are shooting RAW the histogram is essentially useless.

The histogram is from the basic JPEG RAW generates so there is something to display on the camera LCD.

As far as print sizes and images on a CD.

I was wondering paulpippin29 if you have investigated the issue of print size aspect ratio's and what you will do when your clients contact you to complain that the 5x7 prints they just had made from your 8x12 CD image have half of auntie Edna cut off?

paulpippin29 · Jun 27, 2009

Well, that's why I was asking what the optimum resolution for print would be. I simply figured that with a full resolution image, you'de be able to print any size you want, though I could be wrong. I would think that it works like basic resizing... wheras... resizing an image down to a smaller size always looks better than resizing a smaller image up to a larger size... but, I'm just now diving into the whole print thing, so I'm probably wrong about it all... just seems like it should work that way, and if it were to work that way, I'de want to give the client the optimum res, allowing him or her to print any size they wish, without cutting off anything. I am aware of aspect ratio's when resizing images, and would hope it works the same way for prints, but again, I'm probably wrong.

Here is a full screen image of another test shot (I did not keep the original test shot from which the crop was derived) taken of the same flower, this time, the sun had come out. It's in RAW format, loaded up in ACR, and all I did to it was use the "AUTO" feature of ACR, then boosted the clarity to +75. If you'll notice, ACR did not alter the exposure in any way. This image also had the same noise at 100%.

musicaleCA · Jun 27, 2009

Maybe I'm not pixel-peeping my photos. I mean, there's going to be some noise, but your camera should be acceptably clean at 100. If it isn't, eh, just toss some noise reduction at it.

As for printing, aspect ratios are the same deal. If you have to create a print at a different aspect ratio, crop, don't resize.

And don't resize images to larger sizes to get an image for a larger print. It just doesn't work; makes the image blurry, unless you're using really advanced software like Genuine Fractals that can blow-up images by rather absurd ratios without losing much detail. The optimum resolution for printing is, er, well, kinda sorta the largest resolution file you have on hand. That said, the larger the print is, the lower PPI you can get away with, because the image is going to be viewed from a greater distance.

ImageKind has some useful information on this on their website, here.

paulpippin29 · Jun 27, 2009

Exactly musicaleCA... that's what I was saying about resizing. I knew that enlarging an image would degrade it's quality for print, or any other application for that matter. So this is why I thought by giving the largest res I have to a client, it would therefore allow them the maximum amount of possible size options when printing.

As far as pixel-peeping goes.... I'm a bit picky, yes, but I'm not over analyzing the image at all, I wish I was. I mean, the crop up top says it all. That's the noise I'm getting, at low ISO's. 100 and 200 are all I ever use, and 200 is used only in low outdoor lighting, or extreme cloudiness, as it was when I took that first image. The wind was blowing a bit, so I had to up to 200 to get my shutter fast enough to freeze the flower.

I did notice this one thing however while playing around a little bit ago... it seems that the noise will increase, or decrease substantially when I alter my white balance. In the image up above, you can see that I had the white balance set to "DayLight"... but if I switched it over to Auto, the noise almost went away entirely. < This makes no sense to me, and I hate that too. The above image did not look right using the AWB, but looked much better using "DayLight".

Oh well, who knows... maybe I am being to picky, over-analyzing a bit to much, or perhaps it's this kit lense of mine. The main portions of the noise are most visible within the background blur "bokeh", while the main subject, particularly at the focal point, has no noise at all.

three_eyed_otter · Jun 27, 2009

Have you considered your DOF, i.e., aperture?

In the latest photo posted there is only 1 petal that is sharp, the curled one, and only part of the petal (the nearest) is sharply in focus.

have a good one
3Eo

musicaleCA · Jun 27, 2009

More noise at different WB settings?

I can see how that makes sense if there are different colour temps on the scene...I'm not a colour balancing expert like a few here though. Maybe you should poke Garbz about that. :greenpbl:

A better lens will focus light better; you'll probably end-up with a little less noise as a result. If you get a better lens you'll definitely see an improvement in IQ though, no matter what (I've really got to stop touting the benefits of better glass, or I really am going to go out and buy that 24-70 I'm fawning over... :lol: