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05-22-2012, 12:52 PM   #1
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What causes breakup of verticle lines?

I recently bought a Pentax K2000 and have been shooting various shots around the neighborhood to help famiiarize myself with the camera and test the quality of images from different lenses. I notice I get a "breakup" of verticle lines, as shown in the two photos included. Especially, take note of the breakup of the line behind the doorframe of the blue truck....and the support post on the shot of the front of the house. What causes this and is there anything I can do to emiminate it? The photos were shot using the Pentax DAL 50-200 lens that came with the camera and the camera was set on "Auto Pict" with an ISO of 400.





Thanks for any help or advice you may offer.
Dewman

By the way, this is the very first auto focus DSLR I've ever owned and IM LOVIN' IT! The auto focus is such a great help with these 66-year old eyes!

05-22-2012, 01:01 PM   #2
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05-22-2012, 01:22 PM   #3
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O.K. I read the explanation and it makes sense....sorta'....but, am I to understand that it's just something I've just got to learn to live with? I shot the photos on the highest resolution my camera offers, that being 10.2 MP and the photos posted are without any cropping (or at least very minimal.) Am I missing something here? Would the fact that I shot them at or near 200mm have any bearing on the results? Or....does my camera have an internal "cure" for this problem? Keep in mind, I'm totally new to digital photography, so please forgive any "dumb" questions.

Thanks,
Dewman
05-22-2012, 01:31 PM   #4
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Known as jaggies.... seems to be a pentax thing lol. Ive not seen them that severe before though. They genraly only show with JPGs and genraly only visable at very large sizes or 100%. Its just down to pentax choosing and or opting for a very light anti aliasing filter. It does allow for exceedingly fine detail though.
Shooting raw should eliminate it. These have got to be 100% crops ? They also seem a tad over sharpned sumhow too.
Whats with the second pic lol it looks like a bad wallpaper job !

05-22-2012, 01:32 PM   #5
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It is caused by jpeg compression, not the camera per se. I shoot RAW, never see anything like that ever.
05-22-2012, 01:38 PM   #6
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Check the custom image settings. The previous owner may have increased the sharpness setting. When I was shooting JPEG with the K-x I preferred the Natural custom image because it has slight negative sharpness.
05-22-2012, 02:02 PM - 1 Like   #7
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Interpolation

That is caused by aliasing when the photo is shrunk to a smaller size. If you are saving the full-size JPEG or RAW file from you camera and you print from that, you won't see these artifacts on a print.

On your monitor, when you view the photo at any size other than its native resolution (100% or 1:1), you might see this effect on straight lines. The sharper the original image is, the more pronounced the effect. To fix this, you need to pay attention to the interpolation method used for resizing. If you are using GIMP (free) or Photoshop to resize your images, you can select the interpolation method when you resize. There are several options, but anything other than "none" will get rid of the effect shown in your images above.

I attached two images as an extreme example of aliasing. The first one had no interpolation applied when resizing from 3000x4000 pixels to 300x400 pixels. The second used interpolation when resizing to 300x400. The only difference between the two is the interpolation method. No changes to JPEG settings, sharpness or anything else. As a bonus, the interpolated file is more than 20% smaller than the non-interpolated file at equal JPEG quality.
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05-22-2012, 02:12 PM   #8
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See the bit where it says sharpness and detail etc.... they explain it better than I can !

05-22-2012, 02:15 PM   #9
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Hey, the 1980's called, they want their image editor back. :-)
What software did you use to resize your image?
It looks like the result of a very poor resizing algorithm. (thus, like something from the 1980's) :-)

As stated, GIMP will do an excellent job. It is generic.
If you have a Windows PC, IrfanView is small, fast and does a most excellent job with resizing images (does them in batches as well).
On Mac, I have found nothing that compares. Although the built in Preview application does a great job, its just not as versatile.
05-22-2012, 02:18 PM   #10
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Not to mention infranview is free lol
05-22-2012, 02:33 PM   #11
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@amoringello: I used GIMP to resize both with different interpolation settings on each ("None" and "Sinc"). The ugly result is from using no interpolation, meaning no algorithm at all. I also used pretty strong sharpening on the full-size file to make the effect more obvious for demonstration purposes. I guess it's also an example of why sharpening should be the last post-processing step. I think GIMP usually defaults to "Cubic" interpolation so you wouldn't normally see such an ugly result.
05-22-2012, 03:16 PM   #12
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O.K......I suppose I need to do a WHOLE LOT MORE READING, because I'm totally lost when it comes to some of the nomenclature you're using. Such as "interpolation," "algorithm," "aliasing," "RAW," "JPEG compression," et.al.

I took the photos, then used a program that came with an old Olympus 3.2 MP camera I bought about 10 years ago to download them to my PC....so I suppose that's the root cause of some, if not all of my problems, you suppose? I use it because I KNOW HOW to use it. Part of the "Old dog, new tricks" syndrom, I guess. I then took them to "Print Shop" to downsize them to a usable size for posting. hehehe....I can hear the groans all the way here in Idaho! I did NOT do any editing to them, such as saturation, contrast, sharpen, or anything. Really, I DIDN'T! They're all full size (as in not cropped), although I did resize them to 600x414 for posting purposes.

I also have the program that came with my Olympus 14MP "pocket camera" that I can use to download/resize them, but have never tried that option. I also have "Photoshop," for what it's worth. But, from what you've said, none of the methods I've used so far is acceptable, right? Dumb question. The results so far would indicate IT ISN'T ACCEPTABLE!

I guess the good thing is....I CAN get rid of the "jaggies," it's just a matter of learning some new techniques to download them, resize them, new camera settings and so forth, right?

Jeez....so much to learn and such a small amount of grey matter.

Thanks for the tutoring. I appreciate it more than you realize.

Again, I apologize for not contributing anything to the site other than to ask questions.

Dewman
05-22-2012, 03:21 PM   #13
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Just invest in a decent program. No need to spend a fortune... check out corel paintshop pro X
you would love it !
05-22-2012, 03:24 PM   #14
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QuoteOriginally posted by westmill Quote
Known as jaggies.... seems to be a pentax thing lol. Ive not seen them that severe before though. They genraly only show with JPGs and genraly only visable at very large sizes or 100%. Its just down to pentax choosing and or opting for a very light anti aliasing filter. It does allow for exceedingly fine detail though.
Shooting raw should eliminate it.

These have got to be 100% crops ?

If you mean "full size," like the same size as I shot them....yep. No cropping.

They also seem a tad over sharpned sumhow too.

Nope, I didn't "sharpen" them.

Whats with the second pic lol it looks like a bad wallpaper job !

What it means "A bad wallpaper job"? It's just the neighbor's front yard. I didn't do any editing to it. Nana. Zip. I promise!
I appreciate the help. Thanks.
Dewman
05-22-2012, 03:31 PM   #15
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Your welcome. the wallpaper part was me being a little sarcastic lol Its because the second pic litraly looks like its been cut up and place back together.
In all honnesty Ive never seen that before lol
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