Confused about dpi

[Mullet]

When I open up my pics from my camera the dpi is 72 . If I want to change that to 300 let's say, do I simply make that change by putting in the new number or is there a process to go thru to do it right?????

Thanks for the help. I have been a member here about 2 weeks and the sheer volume of info I have absorbed is amazing. I love this site

[CyberPet]

You need to un-check the box at the bottom (I think it's something like "change resolution" or something like that in english - I have a swedish version), that greyes out the pixel dimensions, so you can type in 300 in the resolution box and you'll keep the same pixels and get the right resolution (and size in inches or cm).

[Mullet]

You do that under image size??

[Curtis N]

I wouldn't sweat the DPI thing too much. It's really not a very useful specification. How you change it depends on what software you're using.

If you print the files yourself, in most applications you can select the print size you want with printing options. If you give your files to a local lab or upload them to a lab for printing, they will fit the image to whatever print size you order. They don't even consider the DPI setting.

[LadyHawk]

This is what you want to do in Photoshop to replace the 72 pixels/inch (ppi) setting (this is usually the default setting for digital cameras).

Go to the image menu, choose image size to bring up the Image Size dialog box.

Under the Document Size section, the Resolution setting is 72 ppi. This is considered "low resolution" and is ideal for images viewed online, but it is too low for high-quality results from your ink-jet printer. Proceed as follows:

1) Make sure the Resample Image check box is unchecked (off), then

2) Type in the Resolution setting you need, such as 240 or 300 ppi. Photoshop will automatically adjust the width and height of your image in the right proportions. There is no loss of quality with this procedure.

Welcome to the forum!

[Poco]

Oh, here we go again...

There have been some other threads about this recently - see if you can find them.

As Curtis said, the DPI settings in your file are almost totally irrelevant. I say almost because if you select File->Print from within Photoshop it will try to print using the DPI that is embeded within the file (so an 8MP image at 72dpi will take 20 sheets of 8x10 to print). But you will probably never do this. You will probably print a specific size, like 4x6 or 5x7 or 8x10. This in in the "File->Print Layouts" option in PS Elements 2.0, I don't know about other versions. Or you will send the pictures to a printing service like Walmart and ask for a specific size. They will not look at the DPI settings in the image.

There really should be a sticky about this somewhere.

[Jesper]

Please do a search in the forums for the words "dots per inch", you'll find a lot of posts about this.

Short answer: the DPI number is irrelevant. It does not say anything about the resolution or quality of your image, so you can just forget about it. It only becomes relevant when you want to print your image.

[CyberPet]

Actually, the dpi value is only important if you work with software like InDesign and don't want to scale down a huge picture all the time to size. I.e. if the image is set at the right dpi, you can mount the images in InDesign more quickly... i.e. it save you a few minutes of work... and when you do a book, like I do, it saves you hours.

[Poco]

Actually, the dpi value is only important if you work with software like InDesign and don't want to scale down a huge picture all the time to size. I.e. if the image is set at the right dpi, you can mount the images in InDesign more quickly... i.e. it save you a few minutes of work... and when you do a book, like I do, it saves you hours.

Right, so if you plan to publish your photos in a book or newspaper then the DPI is relevant. Otherwise it isn't.

I think the key here is that if you aren't sure about the DPI or how (or why) you would want to change it, then you probably don't need to. You will know it when you need it.

[CyberPet]

Poco, correct! Only when you need to send them off to somewhere for publishing, it becomes more important.

It's the amount of pixels that counts anyway... and you *can* send your 72 dpi pic to a printer too... they'll scale it to size, since you will keep the same pixels as the original.

[Mullet]

Wow, thanks for all the responses. Here is why it came up. I had left the pics at the 72 dpi and resized the image to 6 x 4. I uploaded my pics to wink flash and got a whole lot of warning s about resolution too low to print. The pics could be printed but quality maybe an issue according to the warning. I apprecaite everyone input on this!

[Poco]

You may have already figured this out, but when you are uploading your photos to a service like this you don't need to resize anything. If you purchase a 4x6 photo you will get a 4x6 photo from any file you give them, regardless of DPI or resolution so, in general, the higher the resolution the better. Just don't resize the photo and you will be fine.

The only time you might want to resize is if the print size ratio doesn't match your own. So if you take photos with a P&S the ratio is not 4x6, closer to 5x7 (Think of it like Normal vs. Widescreen TV). So if you upload those photos they will crop a bit of the top and bottom. If your subject is in the center of your photo or if this is exactly what you want then this may fine.

You may want to be explicit as to exactly where the 4x6 portion of the photo comes from and crop them yourself before uploading. This can easily be done in photoshop (there are some threads around describing that procedure) just make sure you set the relative ratio (not absolute size) when cropping. Then Photoshop will make sure that the widthxheight is 6x4 regardless of the actual pixels and you can crop exactly where you want the photo (but don't resize!).

[LadyHawk]

When I open up my pics from my camera the dpi is 72 . If I want to change that to 300 let's say, do I simply make that change by putting in the new number or is there a process to go thru to do it right?????

Thanks for the help. I have been a member here about 2 weeks and the sheer volume of info I have absorbed is amazing. I love this site

I don't understand why everyone keeps referring to the camera's default 72 ppi (pixels per inch) as dpi (dots per inch). They are two different things!!!

You will have to weed thru responses to determine whose advice is correct, Mullet. My post above is almost verbatim from one of Scott Kelby's books. He is the editor of Photoshop User Magazine, and author of many books. I'm not an expert, but he is. ;)

[Poco]

All we are trying to say is that, unless you are publishing the photos in a book or newspaper or magazine and you are required to submit them in a particular format, the ppi or dpi is irrelevant. There is no reason to ever change it.

If you submit a 6000x4000 image to wink flash and ask for a 4x6 (6x4 really) print it doesn't matter whether the dpi or ppi in the image is 72, 300, or 5000 - you will get the same result.

If you are sending your images to wink flash then any time spent fidling with dpi, ppi, or the dimention in inches is a waste of time and, in fact, may result in you making the photos worse.

This is why Mullet is getting the errors from wink flash. By changing the size of the image to 6"x4" you reduced the number of pixels in the image since the "ppi" was 72 it would make an image that is only 432x288, way too small for a 6x4 print. Inches are irrelevant (except in the previously mentioned examples). Always work in pixels - the more the better - and don't ever reduce the resolution before printing (unless that is the effect your are going for).

At most - crop the image to more appropriate dimensions or for a better framing (zoom in a "bit" on your subject) - don't resize.

Now, that said, I have had some panoramas that were way too big for the local print shop to accept, but we are talking 30-40MP but I doubt you have any images that size.

[Mullet]

Thanks again everyone. I uploaded without changing size and it worked like a champ. I appreciate your pateince