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Old Nov 12, 2006, 8:02 PM   #1
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I just bought an nice used Olympus C5060 (5.1 megapixel) to replace my C3030 and I was wondering about the image resolution. When I use any of the higher resolution image settings, and then pull the image up in Photoshop for retouching etc, they are only at 72dpi.

Even at the TIFF setting, the images still seem a bit grainy. It seems the various image settings on the camera only refer to physical size of the image, and not necessarily the dpi of the image. Am I simply confused? Which mode would provide a higher resoltion shot? A TIFF or a JPEG at the same resolution at say, 2592x1944?

Thanks for any help or guidance!

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Old Nov 12, 2006, 9:45 PM   #2
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The 72 ppi is just a default setting, it doesn't actually mean anything really since ppi only means something when you actually print out , when the pixels available are divided over the size of the print.

Indeed as I am sure your editor shows you that setting would print out at something like 36in x 27in !

Final pixels per inch depends on the final print size, so for your camera you would have at best

4 x 6 = 432
5 x 7 = 370.29
6 x 8 = 324
6 x 9 = 288
8 x 10 = 243
8 x 12 = 216
8.5 x 11 = 228.71
10 x 13 = 194.4
10 x 15 = 172.8
11 x 14 = 176.73
12 x 16 = 162
12 x 18 = 144
13 x 19 = 136.42


In other words, shoot at the highest resolution you can and ignore the preset ppi value, since its very likely you will never print at that size.

PPI and DPI are not the same.

See, http://www.mattspinelli.com/ppidpi.html
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Old Nov 12, 2006, 10:18 PM   #3
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Thank you so much for the reply. The articles your referred were indeed enlightening.

I'm still a bit confused.

Most of the images I am taking from the camera are being use for print and printers require 300dpi images. Some are being used for web only, but the higher quality allows for finer detailduring the touch-up process in Photoshop.

When I take the images into Photoshop, even those taken at the highest resolution, after touching up, will only save at 72dpi.

I may be missing the entire crux of your article. Trust me, I am not dense, just confused. Do I want to use the largest resolution setting on the camera? (The camera runs very slow saving shots at this setting). I'm looking for the most detailed, clear images, versus larger print sizes.

I'm also a bit confused how the print sizes you listed above refer to the image settings on the camera. In other words, what resolution would be 4x6 which you list as the ppi?

The basic resolutions available on the camera are 2592x1944, 2592x1728, 2288x11712, 2048x1536, 1600x1200.. (and on down)
and the modes (which the manual does not explain very well) are RAW, TIFF, SHQ, HQ, SQ1 and SQ2.

Thank you again,
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Old Nov 12, 2006, 11:10 PM   #4
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Always shoot at the highest resolution possible.

The modes listed as SHQ, HQ, SQ1 and SQ2 are the jpeg quality settings.

Jpegs are compressed (just like for example mp3s), the more compression the smaller the files, the faster they save to the memory card, and the smaller amount of space they use. Downside ? More compression, more compression artifacts, more smeary or blurred it looks. So always use the least compression, the highest quality.

RAW is uncompressed data, a bit like a digital negative, you can't display it until you process it , yet it gives you the highest control over everything, you can change white balance, etc etc, unlike jpegs which are processed in camera and cannot be altered easily later. RAW files are huge though, and it takes time to get to know how to process them properly.

As for the print sizes i listed..

Your camera takes pics at a highest resolution of 2592x1944 which is a ratio of 4:3

Common print sizes such as 6x4 are a totally different ratio, a different shape, ratio 3:2

So, to print out at these sizes either you crop the photo losing information around the edges, or you print the 4:3 ratio inside the 3:2, which gives a white border...

So, you want to print out a 4x6 photo.

Well, your pics are 2592 pixels wide, so 2592/6 = 432 pixels per inch

The height of the print out will be 4 inches , 4 * 432 = 1728 pixels.

So, your 4:3 photo at 2592 x 1944 becomes when converted to 3:2 ratio for printing at best 2592 x 1728 pixels which is a ppi of 432.

Due to the ratio differences you lose the other couple of hundred pixels..

In reality your ppi will be even less, as you may want to crop further into the photo, to improve the layout, to get rid of distractions or to focus in closer for a specific effect.

You can just leave the files at 72ppi as it matters not.

If you look at the actual size reported , if you printed your full size image at 72ppi then the printout would be 36x27

If you really want to change it then resize it and change the resolution from 72 to 300.

Make sure resample is not ticked.

You will notice that the actual print size reported changes from 36x27 to 8.6 x 6.4

Remember printing determines the ppi, not just a setting embedded into a photograph.

72 is a typical default, but changing it to 300 or any other number, neither adds nor subtracts the number of pixels you started with (assuming you have not resampled).

Number of pixels / number of inches actually printed.. thats where ppi comes into play.
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Old Nov 14, 2006, 12:22 PM   #5
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TaraD wrote:
When I take the images into Photoshop, even those taken at the highest resolution, after touching up, will only save at 72dpi.

Take another look. Besides DPI, photoshop also tells you what SIZE the image is. There's a HUGE difference between a 4" by 6" image at 72 dpi and a 24" x 36" image size at 72 dpi.

As long as you don't change the image size, keeping things at 72dpi doesn't mean a thing. Just view the image at 'original size' to see what I mean. This is why you have to be careful with some image editors when doing crops. You need to be sure you aren't changing the overal image size when you crop down a little bit. It's also why the 'preset' crops in photoshop (e.g. 8x10, 5,7 etc) have a dpi associated with them. You'll notice that they say (8x10, 300dpi). When you use those, you are getting rid of excess image resolution.

And, as already stated - always shoot at the highest resolution your camera allows. Memory is cheap and you never know when you will want to print a large image or want to do a heavy crop.

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Old Nov 14, 2006, 10:25 PM   #6
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Thanks guys for all the insight. I think I've got it now.

I assume most of this does not matter if the images are used for web, since image size reduction will generally make an image much "clearer".

If I use Photoshop to resize a 2592x1944 image (without cropping) to, say, 1000x750, I assume there will be no lose in image quality for web use.

But for printing, I've learned much here, and how not to allow Photoshop to resample when resizing for printing.

So... I will now shoot at 2592x1944 at the lowest compression which is SHQ.

(And the camera DOES have a 3:2 setting for the 2592x1944 resolution, just in case)

You've all been a big help!


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