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02-17-2013, 03:59 AM   #1
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Image size vs quality

Has anyone noticed any quality degradation when using camera in lower image size then native 16MB.

I dont think I will ever need full res pictures so I would like to save some space on HDD however I would still like best picture quality.

Thanks

02-17-2013, 04:40 AM   #2
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External HDs are cheap. Cameras that shoot excellent quality 16MP files are expensive. My advice would be not to throw away image quality that your camera is capturing, and simply invest in some additional storage!
02-17-2013, 04:47 AM   #3
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If you want best image quality you should shoot raw and use raw editing software.
Making images smaller often actually improves the perceived quality, it makes them look sharper and removes some noise. But on the other hand, you lose fine detail and if you want to make prints, having a bigger image (higher resolution) can help.
So the optimum between image size and quality is a personal thing, you will have to decide for yourself. But as long as you keep the actual "quality" (the number of stars) high enough, the image will look good regardless of MP.
02-17-2013, 05:49 AM   #4
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As an option, you can always save your RAW files as compressed DNG files. You'll need Adobe's LightRoom 4 or perhaps their (free?) DNG converter.
It uses lossy compression, so the file sizes are much smaller. Some detail is obviously lost, but I have not seen a discernible degredation in quality. Most of the benefits of raw remain in tact and is still well above the limitations of JPG.

I have no doubt that fine tonal transition and maybe even fine pixel detail is lost at some point.
But if disk space is an issue, I would go this route long before I reduced the initial image size.

I would also add that any work I sell or for which I expect to do a lot of post processing will remain as full size raw DNG.

02-17-2013, 06:34 AM   #5
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I think you would notice. A while ago I experimented with 12MP jpg files from my Samsung P&S and there really was zero loss of any detail by selecting the 8MP option so that's what I've always used with that camera to save space. The perceived detail was still less than my 6MP K100D files converted from RAW though. The difference however is that the K-30 has 16MP worth of real detail, so any reduction in MP will lose some of that precious detail.

From what I've seen of the Nikon D5200 24MP files, if I owned one I would seriously consider a 16MP filesize if that were an option as I'm blowed if I can see any real extra detail going to 24MP on APS-C compared to the K-30. I think 16MP is about optimum for APS-C, 20MP tops.
02-18-2013, 04:29 AM   #6
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QuoteOriginally posted by amoringello Quote
As an option, you can always save your RAW files as compressed DNG files. You'll need Adobe's LightRoom 4 or perhaps their (free?) DNG converter...
I do not understand. The questions of OP (original posting) are place in K-30 forum and about JPG. So RAW-DNG conversion is not required for K-30.

If you like to save memory, I would recommend to use just DNG from camera without additional JPG file. I am even converting the original DNGs and replace the embedded full size JPG preview with a medium size JPG preview. For this I use free! (no question mark) AdobeDNGConverter. So the original DNG from K-30 (4928x3264 pix) are reduced in size from e.g. 12.641 MByte to 10.544 MByte. The medium size preview JPG is really small. If I generate a DNG without preview, the size in this example would be 10.512 MByte. So the embedded JPG preview is only 32 kByte. Note that the updated preview no longer includes K-30 lens correction.

Summary for one example image 4928x3264 pix taken with K-30 and converted with AdobeDNGConverte v7.2:
  • Original JPG: 5.941 MByte
  • Original DNG: 12.641 MByte
  • Extracted JPG: 1.628 MByte (extracted with ExifTool from original DNG)
  • Converted DNG: 11.320 MByte (updated full size preview, does not make really sense)
  • Converted DNG: 10.544 MByte (medium size preview, 1024x678 pix)
  • Converted DNG: 10.512 MByte (no preview)
The only special thing I do is, that I export the embedded full resolution JPG preview to a separate file with ExifTool before my DNG preview conversion. This, because I like to have the lens conversion of K-30 just for comparison, which is only in the original JPG preview or original separate JPG file. But I do not need the high quality and size (e.g. 6 MByte) of separate JPG and can live with the smaller export size (e.g. 1 MByte) of embedded full resolution JPG preview. If you really need high JPG quality there is always the DNG available for all kind of raw processing. I can recommend strongly the medium size preview DNG. Not only the file size is smaller, but also every image software tool, which is not able to process the raw content will display or process only the medium resolution preview. So you can detect very easy, if something is not working properly in such software. With IrfanView for example there is another benefit: The display of preview is much faster, but you still can define in the program settings if you like the original raw or half-size raw image be used for display (which is of course much slower).

Yes, any reduction of JPG size and compression is immediately visible as degradation. Sometime not so obvious, but often you can detect it very easily when looking for small details in zoomed mode or for slightly changing color areas in the image (e.g. blue sky).

Regards, Peter

Last edited by Plentax; 02-18-2013 at 04:51 AM.
02-18-2013, 06:22 AM   #7
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QuoteOriginally posted by Plentax Quote
I do not understand. The questions of OP (original posting) are place in K-30 forum and about JPG. So RAW-DNG conversion is not required for K-30.
Sorry. I think I missed one word and caused confusion. What I meant to write about was "Lossy Compressed DNG". Not merely Copressed DNG.

If saving space was the issue, using RAW (PEF or DNG) is going to go a long ways towards doing just the opposite when compared to JPG!
Actually, Lossy compressed DNG is not going to save a lot of space either, as it is comparable to a standard JPEG.
But it is going to give a LOT better pictures for not a lot of disk space gain. (Lossy compressed DNG still retains the 12/14bit nature of the image)

I think the general consensus was merely that reducing the image size will in fact reduce quality, perhaps to an undesirable extent.
Rather than being concerned about file size or disk space, the image quality should com first.

I was simply giving a potential reasonable option for retaining much of the benefits of raw PEF/DNG without doubling or quadrupling

I have a K5, stillMP, but K-30 might have better compression? My file sizes are slightly larger. :-) Still, I see the following;
Standard JPG, about 8MB.
Standard DNG (from camera) about 22MB
Standard DNG from camera lossy compressed via LR4 is about 6-8MB.


- Disk space is cheap.
- Reducing image size in camera greatly affects image detail.
- In camera raw (PEF and DNG) are much larger than standard JPEG
- Lossy Compressed DNG (using LR or Adobe DNG converter) is going to save a lot of space over standard DNG/PEF.
- Lossy Compressed DNG will use roughly the same space as a standard JPG.
- Lossy Compressed DNG will have far superior quality with regards to editability than a standard JPG
- Lossy Compressed DNG will not have visual affect on the image. (although, yes it is lossy compression, so extreme processing can naturally be expected to show loss in tone and detail when compared to a normal raw DNG/PEF file)
02-18-2013, 08:52 AM   #8
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QuoteOriginally posted by m112 Quote
Has anyone noticed any quality degradation when using camera in lower image size then native 16MB.

I dont think I will ever need full res pictures so I would like to save some space on HDD however I would still like best picture quality.

Thanks
There's no quality degradation in going from 16mp to say 10 or 6 mp. Besides the obvious loss of resoluion of course.
I do the same myself. Unless I know I want to print large or crop heavily, I shoot 6mp jpegs. That's enough for the
occasional small print, and my handheld family snaps are rarely good for anything better than that. As you can probably
tell, I'm not exactly an artist... :-)

Regards,
--Anders.

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