[justinr]

Very nice, were the soft ones from after or before the pub.
Happy St. Paddies day!

Thank you, it was a good afternoons shooting with some reasonable results. Didn't get to the pub though as I still had the drive home. Might just make up for it this weekend if plan A works out.

[GoremanX]

# Most raw formats do not use compression or implement light lossless data compression to reduce the size of the files without affecting image quality. But some others use lossy data compression where quantization and filtering is performed on the image data.[14][15] Many recent cameras let photographers choose between no compression, lossless compression or lossy compression for their raw images.

The PEF and DNG formats are losslessly compressed. DNG in the K10D and K20D isn't compressed at all. This is established fact.

[justinr]

I don't know why you struggled to do A4 prints with the DS. I have made many 11X14 and 16X20 with mine. And they must be good enough, they sold.

I don't know why either, some do some don't, which is why I thought 67% extra pixels would be handy.

[Marc Sabatella]

First, I stand corrected on the nature of JPEG conversion algorithms and the compression - if others say it *is* possible for the K10d to achieve higher compression for the same quality, then I accept that. I thought I had read it all came down to the value of "Q" chosen in the compression algorithm, but obviously my understanding was incomplete.

Second, I don't see any factual errors in the wikipedia article posted above regarding RAW. Nothing in the passage quoted in any way contradicts what I wrote. I'm not sure what you aren't understanding correctly here, but it seems *something* is not just not clicking for you. Not sure how to fix that. But to be clear: Wikipedia is *not* claiming the uncompressed nature of RAW is what makes it great - on the contrary, it is stating plainly that RAW often *is* compressed. Perhaps you are taking note of the fact that Wikipedia states that some manufacturers may provide the *option* of lossy compression whereas I said that RAW compression was lossless? This being a Pentax forum, and my experience and your questions all being about Pentax, I assumed we were talking about Pentax. I have no insight into what other manufacturers might do, and accept that others might optinally provide lossy compression on their RAW files.

Anyhow, if the K10D really is pulling off more effective compression for the same quality - or even if it is sacrificing quality slightly to gain the higher compression - you're still almost certainly better off with the 10MP file than the 6MP even though the file sizes are similar.

[justinr]

DNG in the K10D and K20D isn't compressed at all. This is established fact.

Did I say they were? No, which is why they are all the same size.

[GoremanX]

First, I stand corrected on the nature of JPEG conversion algorithms and the compression - if others say it *is* possible for the K10d to achieve higher compression for the same quality, then I accept that. I thought I had read it all came down to the value of "Q" chosen in the compression algorithm, but obviously my understanding was incomplete.

Part of the problem is that most applications (like Photoshop) only present the user with a very simple interface for determining JPG compression. Photoshop is actually a bit generous in this case because it at least gives different baseline options, but most applications only have a slider or a 1-10 scale to determine the level of compression. This is barely scratching the surface of the different options available for JPG compression. Gimp offers up tons more options, but a lot of them are cryptic and most people don't understand them. And even those options aren't all of them. Camera manufacturers (and application engineers) come up with the best combination of options to optimize file size, compression/decompression performance and image quality for a given product. They also make decisions on behalf of the user to reduce the number of headache-inducing options. This leads to confusion sometimes, like when a 10 megapixel image ends up being about the same file size as a 6 megapixel image. But it doesn't mean the smaller file size has less information in it, or vice-versa.

[GoremanX]

Did I say they were? No, which is why they are all the same size.

I'm just clarifying, since the Wikipedia article you quoted doesn't specify details of specific formats.

[GoremanX]

Here's something I came across a long time ago which I found interesting:

Here is a table that provides an approximate mapping between Photoshop
quality levels and GIMP (actually IJG JPEG library) quality levels:

Adobe Photoshop quality 12 <= GIMP quality 98, subsampling 1x1
Adobe Photoshop quality 11 <= GIMP quality 95, subsampling 1x1
Adobe Photoshop quality 10 <= GIMP quality 93, subsampling 1x1
Adobe Photoshop quality 9 <= GIMP quality 91, subsampling 1x1
Adobe Photoshop quality 8 <= GIMP quality 90, subsampling 1x1
Adobe Photoshop quality 7 <= GIMP quality 89, subsampling 1x1
Adobe Photoshop quality 6 <= GIMP quality 90, subsampling 2x2
Adobe Photoshop quality 5 <= GIMP quality 89, subsampling 2x2
Adobe Photoshop quality 4 <= GIMP quality 88, subsampling 2x2
Adobe Photoshop quality 3 <= GIMP quality 88, subsampling 2x2
Adobe Photoshop quality 2 <= GIMP quality 87, subsampling 2x2
Adobe Photoshop quality 1 <= GIMP quality 86, subsampling 2x2
Adobe Photoshop quality 0 <= GIMP quality 85, subsampling 2x2

Notice the lowest allowable quality in Photoshop is only 85@2x2. I was using far worse settings than this in my post from yesterday, 80@1x1 and even 40@2x2.

[justinr]

You know what guys, I've just wasted an hour of my life putting together a note pointing just how stupid you are acting, but why bother?

Get a grip on yourselves here for fecks sake. This is such a minor point and yet you are so determined to prove your superiority, well ban me all you like, I've lost patience with your pathetic hair splitting.

Marc for a moderator you are one stupid fellow in being so frightened of your ego being dented whist Goreman X you ask why you suck at photography. The answer lies all the way through this thread. If you've got to ask you'll never know.

I'm off to do some photography instead. Bad loser you'll smugly say, nope just fed up up with trying to talk to uncomprehending infants.

[GoremanX]

What the heck? Where did that come from? Now my feelings are hurt and here I was trying to help.

edit: you clearly do not understand compression. That's not an insult, we all have our areas of specialty. I wouldn't know how to scrub clean a horse's toes. But pretending we're infants because you have misconceptions about something which you clearly do not understand is rather... infantile.

[justinr]

Ho hum here we go.

Yes I appreciate that you were only trying to help and and I thank you for it but but there was a complete absence of any recognition of where I might be coming from. It's all about perception, you think I'm a wilful and half brained idiot and I perceived you as a patronising geek intent on hammering home some sort of superiority. In a reply to Marc I explained my position and accepted that things might have changed but that simply wasn't good enough for you two.

Unfortunately forums are cold places where we are denied the visual and sensual clues that go to make up so much of human conversation and so misunderstandings can arise, but it takes all sides to appreciate this and back of the gas.

[GoremanX]

Just keep in mind that this is a public forum. Your questions and doubts are completely valid and could be useful to anyone else who reads this thread. So technical replies that explain the whys and hows of things are not necessarily aimed solely at you, but also at anyone else who might have the same questions and happen upon this thread. It's easy to feel targetted with specific comments, but I assure you, no-one (specifically not I or Marc) wants to make you feel stupid. We're just trying to help. If you perceive it any other way, it might be a good idea to step back and reconsider your perspective a little.

[justinr]

If you perceive it any other way, it might be a good idea to step back and reconsider your perspective a little.

A comment which illustrates precisely what I mean. Where in that post is there any sign that you have begun to understand what I am saying? How about you stepping back a little and thinking about how you come across rather than blaming others for percieving an arrogance in your tone.

Tell me, do you read books much?

[Marc Sabatella]

You know what guys, I've just wasted an hour of my life putting together a note pointing just how stupid you are acting, but why bother?

Get a grip on yourselves here for fecks sake. This is such a minor point and yet you are so determined to prove your superiority, well ban me all you like, I've lost patience with your pathetic hair splitting.

I don't know where this came from. I was simply trying to help you sort through your confusion on a couple of issues by trying to clarify some technical matters. Nothing has "changed"; there was just something you never understood correctly in the first place, and that's what led to your confusion. But if you'd rather stay confused, that's fine by me too. I was just trying to help.

[GoremanX]

I don't know where this came from. I was simply trying to help you sort through your confusion on a couple of issues by trying to clarify some technical matters. Nothing has "changed"; there was just something you never understood correctly in the first place, and that's what led to your confusion. But if you'd rather stay confused, that's fine by me too. I was just trying to help.

I totally get his point of view. I was really mad when I found out there was no Santa Claus, and then learning about the Easter Bunny on top of that was too much for me to handle. I snapped at everyone for a while after that. It totally ruined all of last week for everyone around me. When long-held beliefs that you based your entire life around get shattered, people tend to get mad. The best we can do is be understanding and move on...