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Old Nov 14, 2003, 11:11 PM   #1
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Default Pixels vs. compression



1) Can shoot at 3200x 2400 HQ, each shot is 2mb
2) Or can shoot at 2288x1520 SHQ, each shot is same 2mb

What factors in deciding which way to go where same 2mb per shot can be accomplished with less compression (SHQ) and less pixels OR
greater pixels and greater (HQ) compression?

My guess would be to go for the SHQ for greater detail though risking what I read may be greater 'artifacts' with greater compression.
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Old Nov 15, 2003, 5:25 AM   #2
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Why do you want a 2mb picture? I guess for me I aim for the highest resolution at the lowest compression...if I wanted to reduce the size of the image or filesize I'd do it on the computer.
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Old Nov 15, 2003, 6:46 AM   #3
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What camera are you using?
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Old Nov 15, 2003, 7:14 AM   #4
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Neither: get more memory and shoot at the highest possible resolution with the lowest compression, i.e., the largest file size. The one(s) you shoot at lower resolution will be the one you would have wanted the largest print or smallest crop. Memory is cheap enough now that if you have to think about that problem, you should get more memory.

If the question still bothers you, do some experiments. Shoot the same thing both ways. Try with a subject that has lots of detail, and try another with less detail.
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Old Nov 15, 2003, 9:57 AM   #5
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It sounds like your using one of the Olympus models with an interpolated output mode.

If it were me, I'd just shoot at the highest (non interpolated) resolution, then interpolate in software later (if needed for extremely large prints to prevent pixelation).

Many software packages have good interpolation algorithms (Bicubic, Lanczos, etc.).

A very good free image editing package, that includes a sophisticated Lanczos Interpolation Algorithm is Irfanview.

You can download it free from http://www.irfanview.com (make sure to download the free plugs-ins too).

Interpolation does not add detail -- only more pixels. You'd be better off using software later to accomplish the same thing (only if you really need it, for very large prints). By using the highest quality, non-interpolated image mode in your camera, you'll get better quality and more detail.
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Old Nov 15, 2003, 11:15 AM   #6
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Default More input on MY posting

For a few years mostly TRV-900 (3 chip) video with its ability to shoot 640x480. Then, added an Olympus C-700 w/ 1600x1200 max. Friend wants to buy the C-700 so I can upgrade to the C-750, so now attending to my learning curve on the basics.

Two replies did not select either of the two listed 'choices' for shooting but agreed I should use the highest resolution at lowest compression which neither choice offered.

(1) offers highest resolution and (2) offers lowest compression but neither offers BOTH.

It could be you were aware of a 3rd choice which I avoided mentioning, which the C-750 does offer and which combines highest resolution AND lowest compression (SHQ at 3200x2400) but is a whopping 8 mb per picture or 32 pictures per 256mb card.

On a related front, I am thinking about adding something like the X storage drive http://www.compgeeks.com/details.asp?invtid=VP-2030 at $89 plus cost of whichever HD you buy or they sell with 20gb HD for only $199. That would soak up 2400 pix at 8mb each. Any comment on this portable storage? Have read great user reviews and this seems to save big $$$ over others being sold.

Soooo , now there are three choices on the digital pix resol. table (1) (2) (neither offering both highest Res & lowest compression) and the 8mb/pix choice that offers BOTH.

Am I correct that non-interpilative(sic) means the highst resol. the camera can ACTUALLY take per its specs? Rather than mimic a higher resol.using theirs or others software?
Look forward to your further thoughts. . All very informative.
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Old Nov 15, 2003, 7:35 PM   #7
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The 3200 x 2400 modes in your camera are interpolated, not "real" resolution.

The highest "real" resolution from your model is the 2288 x 1712 mode, with the highest quality coming from the 2288 x 1712 SHQ mode (other than RAW or TIFF, which take up much more space).

It also has a 2288 x 1520 mode (3:2 Aspect Ratio, better used for 4x6 inch prints to prevent cropping at this print size).

I would avoid using the 3200 x 2400 mode. This adds pixels, not detail, and can actually degrade, rather than improve photo quality, depending on the sophistication of the algorithms used (and you can usually do better using software -- when, and ONLY when you need the extra pixels for extremely large prints).

That's why 3200 x 2400 = 7,680,000 (many more pixels than the camera's sensor is capable of capturing).

As I mentioned in my previous post, you can accomplish the same thing using software (when you REALLY need more pixels, to prevent pixelation at VERY large print sizes). Interpolation does NOT add detail, only pixels, based on the values of adjacent pixels.
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Old Nov 16, 2003, 1:06 AM   #8
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Mike_Peat: You asked ‘Why do you want a 2mb pix’ and added that you opt for the highest resolution at the lowest compression’
Given the C-750 offers 2288x1712 at SHQ (3mb) and 2288x1520 SHQ (2mb) If I’m opting for highest resolution at the lowest compression it seems I should be shooting 2mb or 3mb pictures, shouldn’t I?

Thanks Drew seems all agree highest resolution and lowest compression.

Thanks Jim C on the great explanation of the 3200x2400 interpolation thing.
Seems I’ve seen specs before that note, when mentioning a resolution beyond the camera’s actual capability, that this is done by Interpolation. These specs just refer to Optimum Enlargement Mode (Olympus code words for Interpolation) Guess I should have done the multiplication!

Curious,,,,do you know how large can I print at 3200x2400 using software you suggested for interpolation?

Appreciate the mini course and have a better ‘handle’ than ever on how to use the camera’s allotted pixels. At 10 oz, small size, 10x optical etc. it seems the C-750 offers many features for its price. Know of any other new models with similar specs/price I should consider? Thanks.
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Old Nov 16, 2003, 9:21 AM   #9
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In the 10x Optical Zoom Category, I personally like the C-750UZ (your camera) better than the others in this category (3 to 4 Megapixel Models with 10x Optical Zoom).

As far as the largest print size, you can make very large prints without pixelation, using interpolation. However, this DOES NOT add detail -- only pixels.

As a general rule of thumb 150 pixels per inch being sent to the printer (with an inkjet) is enough to get good prints without any pixelation. 200 pixels per inch provides better quality, with 300 pixels per inch providing the best quality. Again, bear in mind that interpolation can degrade quality, so only do this if necessary.

On a Dye Sub printer, 300 pixels per inch is recomended.

Some subject matter handles larger print sizes better than others. For example: Portraits do a better job, versus a landscape with lots of foilage.

Also, bear in mind that any defects in a photo will be magnified at larger print sizes (noise, Chromatic Aberrations, halos due to sharpening algorithms, JPEG Compression Artifacts, etc.)

Here is a thread discussing the subject in detail. You'll also see some charts in my posts showing the number of pixels (Pixels per Inch) being sent to the printer drivers at different resolutions and print sizes.

http://www.stevesforums.com/phpBB2/v...ic.php?p=76483
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