# Image Size / Resolution Etc Query



## 036 (Feb 27, 2003)

Hi all

OK at the moment here's what I do - I take my pics at the highest resolution the camera allows, with the largest image size. I then use a small portion of this humungous image, or else compress the whole thing.

Would I be better using a smaller image size to begin with as then I would have to compress it less?

Another query: dots per inch and pixels per inch. What's that all about?

Si


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## Stan (Aug 7, 2003)

I do the same thing as you Si. I save the original as master and work from a copy, I reckon it's safer.

If you are careful with compression it can cause less artifacts than using a lower resolution from the camera, from what I've seen.


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## rhaythorne (Jan 12, 2004)

Dots per inch generally refers to the resolution of a printed image from an inkjet/bubblejet printer. The more dots per inch the higher the resolution. Pixels per inch usually refers to the on-screen resolution. The more pixels per inch, the higher the screen resolution.


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## Silver Hawk (Dec 2, 2003)

I do same as you and Stan....maximium resolution on the camera.

and then desktop s/w to reduce the image if necessary. But I do review my JPEG compression setting from time-to-time since JPEG is a lossy format....I never let the s/w do a JPEG save with maximium compression....that does introduce noise.

Virtually all s/w that can save images in the JPEG format will allow you to tune the compression ratio.

Cheers

Paul


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## Stan (Aug 7, 2003)

Agreed Paul.

I still use PSP 7.04, and I still use the export command to determine the compression for each picture if it needs to be a specific file size (as in RLT forum requirements).

I do all of my work on an image before saving it via the export mode, I don't do repeat "saves". Keeps things less complicated and maintains image quality, in my experience.


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## 036 (Feb 27, 2003)

Hi all

I need to try to understand this... so the sensor has lets say 5 million pixels. Presumably with every pic all of these pixels are exposed to a part of the subject. So when I use a different image size what happens? Do some of the pixels on the sensor not get used? Or are the pixels averaged in some way?

Also when I reduce the resolution, does this just make the pixels act in groups together?

How do you all organise your pics? I am finding my pics are getting very disorganised, folders with originals, cropped ones, resized ones... and none of which have a file name anything to do with the subject...

Si


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## LuvWatch (May 14, 2004)

Hi All

If a picture that was taken on max resolution, say 1028 and you then get it on your computer - it would have information on that picture that make's it about 3mb, quite a big file - I see that like a bottle of fine whisky.

Now if I make the picture smaller say 500, then the size of the file gets smaller, say half the size of the original as I have basically gone from 1028 to 500, the file size will be about 1.5mb, but I still have the fine whisky but in a smaller bottle `hic`

Now if I compress the file, it will keep its size of 500 but the goodness is taken out - so instead of a fine whisky, I know have a bottle of cider







but your file size will be smaller perhaps around 200k

The first pic was taken on max resolution but reduced in size to 700 and is 123k










This is the same pic but has been compressed by 50% using my home s/w Adobe Photoshop Elements 3 and is 70k










Now the real buggers are the online photohosting websites, I use Villagephoto's and pay about Â£3 a month - they use recommended compression settings - which I never use - I load them up without compression - here is the same picture but using the hosts compression. The photo is now a measly 31k - not even good cider










Hope this helps - I am off to finish that bottle of whisky









Derek


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## 036 (Feb 27, 2003)

> Now if I make the picture smaller say 500, then the size of the file gets smaller, say half the size of the original as I have basically gone from 1028 to 500, the file size will be about 1.5mb, but I still have the fine whisky but in a smaller bottle `hic`


Hi Derek, that helps, thank you for taking the time to do it. To clarify though (I am a bit dim with all this stuff) when you say "smaller" do you mean by cropping it? Or by choosing a smaller size in the camera?

Si


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## Stan (Aug 7, 2003)

Si,

You don't have to crop to resize. Most graphics packages (PSP, Elements etc) have a resize facility that reduces the image size (whole area) and therefore the file size. This does tend to soften the image that's why I use unsharp mask as my last operation before saving the image.

Most packages also alow you to vary the jpeg compression settings. As I said earlier, I use "export" and adjust the compression with it to reduce the file size. Sublety is important as with any image adjustment, I reckon.


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## LuvWatch (May 14, 2004)

Hi Si

Smaller = resizing the image. As Stan says most software package's will have an option to resize - from the original 1028 to whatever you want - normally about 800 or 600. That is different to cropping, though you could crop a large image down to a smaller size

It is a subject that is difficult to explain and absorb, but could be shown, one to one, in a matter of minutes.

The pic below is a screen shot I took a couple minutes ago and shows the image resize tool. It is showing the image as being 700 pixels wide with a size of 859.3k, with this tool you can then resize the image to suit your needs.










Derek


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