Image Size HELP

[meeza]

Hi, I recently bought a new macbook and a Sony TSC9 Digital Camera. It takes great photos but when I open them up into photoshop (cs2) they are only sized at 72dpi even though I am taking photos at the biggest size which are supposed to be printable on A4. Anyway when I try to resize the Image to 300 dpi which I have done before on an older/worse camera the image becomes quite distorted and does not hold the clarity that the camera takes the photo at.

Can anyone help as I was hoping to use this camera for projects in my Graphic Design degree?

Cheers

[Sark]

The dpi is only relevent to your printer. PS displays the image at your monitors display resolution, commonly 72dpi. The size in PS is determined by the number of pixels, not the dpi setting.

When you decide to print the images the dpi becomes important. You can set this to anything you wish, most commonly between 200dpi and 300dpi for good quality print output.

Changing the dpi will not change the size of the image in PS, but it will effect the size of the printed image, however....

If you check the "Resample Image" checkbox when increasing the dpi, PS will resample the image whilst also increasing the dpi. This will always effect the quality of the displayed image because you're adding pixels to the image.

Unchecking the "Resample Image" checkbox prior to increasing the dpi will have no effect on the displayed image, nor will the pixel count increase, however, the print quality will improve, but at a cost to print size.

Sark

[RTK]

meeza,

All what Sark said.

What's probably happening to you in terms of your "distorsion" when "changing" to 300 dpi:

If you check the "Resample Image" checkbox when increasing the dpi, PS will resample the image whilst also increasing the dpi.

If you zoom in to 100% it will probably not seems as distorted. A huge file (in pixels) will seem kind of jagged and pixelated in PS when viewed at a low zoom level.

The Sony DSC-T9 is a 6 MP camera (Google) - and you will be able to print A4 no problem. An optimal A4 print at 300 dpi would require a file at 2480 pixels by 3508 pixels - about an 8.6 MP camera could do it without any resampling.

However, you still have a lot of information in 6 MP - print at a lower resolution, or resample the file to 2480 by 3580 - and adjust sharpness etc. (whatever does the trick for you). It might not be "optimal" - but most people won't be able to tell the difference, at least not from a few steps back - or using a magnefying glass.

Risto

[meeza]

cheers for your help, I understand what you are saying. However when I view the image at 72dpi at 100% the picture is small but looks sharp when i resize the image with the boxes youve said ticked to 300 dpi, when viewing at 100% the image is larger but is a lot less sharper and more 'blurred,' on the g4 macs I have used at uni when I have done the exact same thing the image has always appeared just as sharp as it was in the first place. I am not sure if this has anything to do with the settings if there is a way to view the image better?

[Sark]

However when I view the image at 72dpi at 100% the picture is small but looks sharp when i resize the image with the boxes youve said ticked to 300 dpi, when viewing at 100% the image is larger but is a lot less sharper and more 'blurred,'

Just remember, the DPI is just a tag stored with the image file. It has no effect on the displayed image, it is just there to instruct the printer how large you want the pixels to be printed. It therefore only effects the images printed size. You could upload an identical image on the web at 72DPI, and 300DPI and they would both display the same and have an identical file size. Changing the DPI in PS should have no effect on the displayed image, unless you check the Resample Image box. Also, bare in mind you should always view the image at 100% in PS to access the effect of resampling, however, this will be displaying at your monitors resolution of approx 72DPI, not the final print resolution.

The approach I would use is as follows.

Open the image in PS and open the Image Size dialogue. Uncheck the Resample Image checkbox. The Document Size shows the size the image will print at the current DPI (Resolution) setting.
Change the height, or width, to the size you want to print your image (the height and width are constrained, so you need to change just one). You’ll notice the DPI will change as you change the Document size. The Pixel Dimensions remain unchanged because you are not resampling the image.
If the DPI increases to above 200 pixels/inch you should be able to produce a good quality print with no resampling.
Unless you’re printing on a high-end printer on top quality Glossy paper, there is no need to print at 300 pixels/inch. Personally, I generally print at between 225 and 245 pixels/inch depending on how I crop my images. This gives excellent results.

If the DPI is still below 200 pixels/inch after changing the documents size, you may need to resample the image. First check the Resample Image checkbox, then change the Resolution setting to your desired DPI. Notice the Document Size does not increase, but the Pixel Dimensions do.

Bare in mind, the more you resample an image the more the image quality suffers. It’s a balance between resampling and printing at a higher DPI, or printing at a lower DPI with less resampling. Experimenting will help you decide which is best. I personally find I can resample an image about 40% to 50% with little loss in quality, although some sharpening is usually required. It depends very much on the nature and quality of the original image.

Sark

Edit
...........One thing that does confuse me is the fact you say the image is sharp, but small, when you first view it at 100% in PS. A 6 MP image should look huge in PS at 100%. What are the pixel dimensions before you make any changes to the image? Also, if you re checking the Resample Image box when jumping from 72DPI to 300DPI, the increase is way beyond what you should hope to achieve whilst retaining reasonable quality. You are also adding far more pixels than required to produce an A4 print.

[meeza]

The image size is at 360x270 at 100% before I make any changes, which I believe for a 6mp camera is small. Ive played around with the camera settings but it does not seem to change a thing! All I was hoping was for large file photos so that I could use them as part of an A4 or A3 design and not end up with a tiny image that cannot be resized without it becoming distorted.

EDIT
I have just checked the image size of the photo when not in photoshop and it is 1200x798, however when I open this file in photshop the image size is 360x270, so there is obviously a problem when opening the file in PS. Anyone have a clue why this may be happening?

EDIT
Ive cracked it I was opening the files from iphoto library so I presume it was only opening the thumb nail, when I open the file from its location in the folder the image is large 2000x2000 + and everything now makes sense!

Cheers for your help.

[Sark]

Some cameras can produce full resolution RAW files with a low resolution JPEG. I had wondered if this was your problem and you were opening the low res JPEG.

6MP should produce a file approx 2000 x 3000pix, depending on your cameras aspect ratio. You now appear to be achieving this. You should now have no problem producing A4 images, and with a little upsampling A3 should also be possible.

Glad to see you've solved the problem.

Sark