Image Size (not Quality but Size)

Olympus OM-D E-M5 Mark III

01/19/2009 09:37:16 PM · #1

I have a question or two (who knows - may turn into three by the time I write this) about image size. My D90 allows me to shoot at three different IQs: 3, 6, 12 megapixel (numbers rounded) but along with each MP I can also choose form small medium and large sizes.

Now this is one fo those Digital Photo things that confuses someone like me who comes from a film background. I have read about it on the interbnet and often see people saying use the largest size regardless of the size of your final output since the small sizes will drop some detail.

But in thinking this through, would not some detail also be lost when taking a huge image and reducing it, say, to the size required for a DP Challenge?

I am not interested in doing commercial photography. Just want beautiful images i can share on the net in forums like this, or make some prints of no larger than 8x10.

One thing I noticed is that so far I have been having a damnable time trying to redcue an image shot at 12MP in the largest size to something considerably smaller. But images shot in the smallest size (still at 12MP) reduce to much more pleasing images.

So am kind of at a loss here. Any words of wisdom in general would really be helpful.

Thankee!

Yo_Spiff

Olympus 12-100mm f/4.0 M.Zuiko ED IS PRO

01/19/2009 09:54:15 PM · #2

JPEG compression is what does it. You need to use the appropriate compression to balance image quality and image size. Every photo is different. I have an explanation accompanying this screenshot.

jtlee321

Nikon D300

Nikon AF-S DX Zoom-Nikkor 17-55mm f/2.8G IF-ED

01/19/2009 10:00:19 PM · #3

If I were in your shoes I would shoot RAW plus JPEG. I would set the JPEG setting to what ever size you prefer, that way you get the image your after and preserving the original in it's full glory. You never know what you may need from that file later in the future. It would be a shame you make a wonderful capture at 6 MP and three years later you sell it to a company wanting to make a billboard out of it. Your just much better off retaining a full resolution image as an insurance policy.

01/19/2009 10:03:06 PM · #4

Originally posted by jtlee321:

I think that's a great idea. The price of even good SD cards is so cheap I could easily do that.

Andrew1023

Nikon AF-S DX 18-105 f/3.5-5.6 ED VR

01/19/2009 10:05:33 PM · #5

I just got a D90 too!

On page 61 of he manual there is a chart that will explain what is going on:

there are three "Quality" settings: JPEG Fine, JPEG Normal and JPEG Basic. All other things being equal, JPEG fine will produce a nicer image, with finer details than Basic. This improved detail comes at the expence of producing a bigger file size (as in, more megabytes and fewer pictures will fit on your memory card). Basic would give you the opposite trade-off: less detail, but smaller file size so you can fit more photos on your memory card.

Now, the final piece of this puzzle is that the D90 lets you set the "Image Size" to Small, Medium, or large. When you look at a "small" image on your computer screen, it may only fill half of your screen, while a "large" one may be so big as to not even fit on your monitor.

Bigger image -> bigger files -> fewer on a memory card -> more detail captured
"Finer" image -> bigger file -> fewer on a memory card -> more detail captured

I skipped a lot of technical details, but that is the basic idea. a "Large" "Fine" jpeg is the most information you can capture, except for using "RAW", but that is another discussion.

As another poster mentioned above, I usually shoot raw for anything I plan on post processing. If I am taking 'snapshots' at a part, i might shoot jpeg to fit more on my memory card... but RAW is my usual choice.

Message edited by author 2009-01-19 22:07:18.

01/19/2009 10:05:53 PM · #6

Originally posted by yospiff:

JPEG compression is what does it. You need to use the appropriate compression to balance image quality and image size. Every photo is different. I have an explanation accompanying this screenshot.

Thanks yospiff! Unfortunately I am not using Photoshop. Have tried a few ways thus far of resizing an image but none have been satisfactory. More research for me I guess.

Hmmm - I actually have a fully legal version somewhere of 6.0. I really have no interest (at least at this point) of anything beyond photo manipulation for things like color balance, sharpness, etc. Maybe I should reinstall it and see how it goes for that.

Andrew1023

Nikon AF-S DX 18-105 f/3.5-5.6 ED VR

01/19/2009 10:09:06 PM · #7

Originally posted by Canopic:

Originally posted by yospiff:
JPEG compression is what does it. You need to use the appropriate compression to balance image quality and image size. Every photo is different. I have an explanation accompanying this screenshot.

Thanks yospiff! Unfortunately I am not using Photoshop. Have tried a few ways thus far of resizing an image but none have been satisfactory. More research for me I guess.

Hmmm - I actually have a fully legal version somewhere of 6.0. I really have no interest (at least at this point) of anything beyond photo manipulation for things like color balance, sharpness, etc. Maybe I should reinstall it and see how it goes for that.

I use Picasa (from google) for my snapshots, and it is a great, easy to use tool for the operations you mentioned... resizing is a snap, too!

edit: and it's free! :)

Message edited by author 2009-01-19 22:09:33.

Bear_Music

Samsung Galaxy S21, S21+, S21 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

01/19/2009 10:10:43 PM · #8

Image "quality" is a measure of how much JPG compression is used; fine is 1:4, normal is 1:8, and basic is 1:16. Image "size" is the pixel dimensions of the recorded image; large is 4288 pixels on the long side, medium is 3216, small is 2144.

The images you shot at the smallest size cannot be 12Mp, no matter what you think you have heard. That's the resolution of the sensor at full size. At small size (2144x1424) you have about a 3Mp native resolution. Notice the relationship of 4288 to 2144: essentially, at "small" size, the camera is recording only half the pixels in each linear direction, to conserve space on the memory card basically. This works fine if you are doing web display or smaller prints, not so well if you blow the image up.

Quality is a measure of how faithfully the camera records the detail within the given size. How important the quality setting is depends on the nature of the subject; if you're shooting "smooth" scenes with little fine detail, it's not important at all: if you were shooting a blank green wall, there'd be zero difference in quality between the different "quality levels" because there's no detail to lose in compression. On the other hand, shooting extreme wide-angle landscapes of complex subjects requires as much quality as the camera can produce to render all that fine detail.

That's it in a nutshell...

R.

Nikon AF-S DX Zoom-Nikkor 17-55mm f/2.8G IF-ED

01/19/2009 10:16:20 PM · #9

Originally posted by Bear_Music:

Thanks Bear. Again I am befuddled in the DP world. I can choose the megapixels on the D90. I an choose, form a spearate menu setting, the image size. So I assume I was flummoxed by rhetoric in the manual and the menus.

Would my basic assumption, though (somewhat modified) be that choosing the small size and the highest megapixels would produce the best image for that smallest size?

(Now this is just an informative question - I like the idea of shooting RAW + Small). Hell, storage media like external drivesa nd writable DVDs are so cheap I could easily store all of the raw images at minimal cost.)

jtlee321

Nikon D300

01/19/2009 10:17:42 PM · #10

Originally posted by Canopic:

Your much better off using the current versions of Elements and Lightroom. Version 6 of PS will not offer the newer versions of the "Bicubic" algorithm such as "Bicubic Smoother" for making enlargements as mentioned earlier or "Bicubic Sharper" for making reductions. Not to mention the editing options that you have in Elements and LR.

Originally posted by Canopic:

You will always be better off shooting with as much detail as possible and letting LR or Elements do the reduction.

Message edited by author 2009-01-19 22:32:59.

Yo_Spiff

Olympus OM-D E-M5 Mark III

Olympus 12-100mm f/4.0 M.Zuiko ED IS PRO

01/19/2009 10:47:04 PM · #11

Originally posted by Canopic:

Thanks yospiff! Unfortunately I am not using Photoshop.

I'm not using Photoshop either. That is a screenshot from Paintshop Pro. $40 on sale at best Buy. The point is that whatever you are using probably has some facility within it to adjust the amount of JPEG compression. You just need to figure out where that function is hiding. What are you using?

klkitchens

Pentax K-1

Pentax FA 50mm f/1.4 AF

01/19/2009 10:56:16 PM · #12

Sing along time!

RAW, RAW, RAW your shots!
J-PEG never use.
You will be much happier,
You will win not lose.

:)

Samsung Galaxy S21, S21+, S21 Ultra

01/19/2009 11:04:42 PM · #13

Originally posted by yospiff:

Originally posted by Canopic:
Thanks yospiff! Unfortunately I am not using Photoshop.

I'm not using Photoshop either. That is a screenshot from Paintshop Pro. $40 on sale at best Buy. The point is that whatever you are using probably has some facility within it to adjust the amount of JPEG compression. You just need to figure out where that function is hiding. What are you using?

Hmmm - I am using Paintshop Pro Photo X2 - (dang but when I see "shop" I think Photo Shop) but so far my resize effrots have resulted in badly pixelated images. I shall try those settings. This is really cool! (Yes, I am 58 years old and I said "cool!" LOL)

Message edited by author 2009-01-19 23:06:39.

Bear_Music

Sony 24-70mm F4 Vario-Tessar T* FE OSS

01/20/2009 12:49:52 AM · #14

Originally posted by Canopic:

For all practical purposes, here's the equation: "size" is determined by the anticipated end use of the image, and "quality" is determined by how much storage space you have available when shooting, and by whether or not you want to transmit the images electronically with a minimum of fuss. Let me expand on that:

1. Most of us who post here in the forums are pretty experienced image post-processors; we'd (for the most part) rather begin with the highest-quality possible recorded image, and then, in PP, set whatever lower parameters are appropriate to the tasked image. In DPC basic editing challenges, for example, that would give us a "size" of 640 pixels and a "quality" of 150kb; but few, if any, of us would be willing to SHOOT at 640/150, even though that's where we are going to end up.

2. Nevertheless, in the Real World most photographers are not like us. Most photographers do what I call "occasional" photography, meaning photography geared around a particular occasion; for example, they shoot their daughter's 5th birthday party, they shoot the family vacation at Disneyland, they do "occasional" photography. And one of the intrinsic elements of occasional photography is that it is meant to be shared. So, whereas in the "old" days this always meant dropping off film and ordering prints, which were then mailed to both sets of grandparents and so forth, nowadays it means uploading image files to the computer and e-mailing them to interested parties. And for that purpose, electronic transmission, given that most shooters do little or no post processing, and given that native image sizes have gotten bigger and bigger as sensors have gotten better and better, Nikon and other camera manufacturers have installed software that (pay attention here) basically resizes and compresses your images in-camera before writing them to the memory card!

Lightbulb going off yet?

The sensor is what the sensor is; nothing in this size/quality options list actually changes what the sensor perceives/records during the act of exposure. Rather, these options change the way the image is post-processed in-camera and how it is stored on the memory card.

Now, the camera is, itself, a little computer; but it can't compare in power and flexibility to the larger, faster computers we use at home. Anything that the camera can do, as far as post processing the image is concerned, YOU can do with more control and more flexibility at home if you A) have the software and, B) have the knowledge to use it.

How does this relate to JPG vs RAW? It's simple; the RAW image is pure data exactly as recorded by the sensor, and the camera does NO post processing, beyond what is needed to organize and record those data in a usable format, before writing the data to disk. When you shoot JPG, on the other hand, completely apart from the size/quality issues already mentioned, you make a host of other decisions which the camera incorporates into its post-processing before writing the data to the memory card. When you choose a picture style, for instance (that's what Canon calls it, not sure what Nikon does) you are choosing between many options for contrast, white balance, color saturation, input sharpening, and so forth; and in a JPG once the data is written those parameters are set in stone.

You can modify them further in PP, but usually not as satisfactorily, results-wise, as what you'd have if you set them "correctly" to begin with. With RAW images, on the other hand, you start the PP with untouched images (they actually look pretty crappy, usually soft and muddy) and you dial in those parameters that, with JPG, you would set in-camera. Why do it this way? Because, with RAW, if you don't like the results, you can toss the experiment and try again with different parameters. So a RAW image is exactly like having shot a dozen or more variations of the same thing, changing contrast, sharpness, white balance, whatever for every shot.

The tradeoff is this: when you shoot RAW, every single shot has to be post-processed before anyone else can even look at it. When you shoot JPG, you can just dump all the images as-is to whoever you want to have them.

But the thing of it is, shooting RAW without solid background knowledge is kind of pointless; there are so many variables to cope with it's quite intimidating. For neophytes at photography, shooting JPG is a better way to start; read the manual, experiment with picture styles and basic settings, do it in a systematic way, until you begin to understand firsthand what effect the different variables have on the image. When you begin to feel the limitations of JPG, then you're ready to shoot RAW. If you have plenty of storage space available, RAW+JPG is a viable option for you; you can store the RAW images for future use if you ever need them, and still do the learning with the JPGs.

Sorry for my long-windedness :-)

R.

Message edited by author 2009-01-20 00:52:40.

tnun

Ricoh GR III

Pentax DA 18-135mm F3.5-5.6ED AL [IF] WR DC

01/20/2009 01:39:19 AM · #15

Grateful for your thorough windedness. It never hurts to be reminded of the sheer enormity of data that is involved; nor to be reminded that because of the size restrictions certain types of photos do not show well in this venue.