dpi for website

[deni]

Hello,

I recently did a photo shoot for a website and the image needs to be in 600dpi. I have a canon 30D. I'am not familiar

with digital too well and don't know how to make the image into 300 or 600dpi. It is all confusing when i read anything

about dpi. I do have photoshop cs3 if that helps.

Thanks for any help in understanding how to change the image.

[bjscharp]

If they want it for the website, dpi doesn't matter at all. Dpi (dots per inch) is only used when printing images. It's stored in the metadata of the jpeg so the printer knows how many pixels to put on each inch of paper.

 

On a website, only the resolution of the image matters (number of pixels). Your EOS 30D produces images of 3,504 × 2,336 pixels (8.2 megapixels), which is too big for most website applications. Ask them what resolution they want the pictures, and resize the pictures.

[rainer_t]

Search Pnet for "72dpi". You'll find a lot of thread about this theme.

 

In short:

 

- dpi values are pretty much meaningless as long as you do not print. (and even than, the dpi value only defines

some sort of standard size for a picture).

 

- You camera will set some default value into the dpi field (canons usually use 72). But this value can be

changed to whatever you want (without any impact on the picture itself).

 

- The really interesting values are the imagesize in pixels and colordepth.

 

If someone really asks for a 600dpi image for web use, its an indication that this someone has no real idea for

what this value is used. Anyhow, ask for the required size in pixel, resample your image to that size, set the

dpi to 600 and be done with it.

 

You might ask, how to set the dpi value ... what software are you using? ... Most SW allows to set dpi to your

needs, but the function is hidden at different places.

[geoffs]

If you have Photoshop.Open your photo in editor.Click on >image at the top,then >resize in the drop down menu then >image size.A window will show with your photo size in pixels.You then change the values as you want and then save as.Give the saved image a different name otherwise you lose your original image.

There should also be a box that you can click to >contain proportions. Tick this box if you want to keep the same proportions as your original image.Such as the common 6x4 ratio,which I believe your Canon uses.?.

[freelance]

For Internet it is the same 600 dpi than 1 dpi. You will see the picture at the resolution of the monitor. Every computer may show it in different ways. Try to change the resolution of your screen and you will see the pictures bigger or smaller. What only matters is the size of the picture in pixels, as B.J. Scharp says.

[geoff_doane]

Although the above information is true, I've found one situation where the DPI of an electronic image does make a difference. When imbedding images in a Word document (whether or not it ever gets printed), I find I need to use a DPI value of 96, rather than 72, to preserve the size of the image in the document. Leaving the value at 72 enlarges the image, and there is some loss of perceived quality.

 

Also there might be some point in saving images at 600 DPI in web applications, in order to try and combat image theft from the website. If someone tried to print the image, it would be very small, although it ought to be easy for anyone knowledgable to change the value.

 

However, I agree that if the only specification for the images is 600 DPI, you haven't been given enough information, and the person asking doesn't really know what they're asking for.

[tri-x1]

Any photo displayed on line that is more than 72 dpi is wasting bandwidth

[rainer_t]

-- "Any photo displayed on line that is more than 72 dpi is wasting bandwidth"

 

That is sort of nonsense ...

 

I show you the same image twice ... once set to 72 dpi and 400x270 pixels

 

The other set to 600 dpi and 400x270 pixels ...

 

and guess what the filesize is EXACTLY the same!<div></div>

[rainer_t]

And now the same at 600dpi<div></div>

[Spearhead]

<i>That is sort of nonsense ... </i><P>It's not "sort of," it's just nonsense.

[rainer_t]

Browsers don't care for dpi ... but Geoff brought up an interesting point about Word ... I assume one could

change the size when embedding the image, but the default size might be derived from the dpi's in the image file.