I have a client who needs slides scanned to make a Power Point type presentation to be used with a computer and projector.

What dpi should I use for scanning, what file type [jpeg vs tiff] and what image size do I need to end up with?

I ususally use tiff files for scanned images.

Thanks for your help.

Powerpoint displays at 72 dpi. However, as a rule I would scan at 300 dpi then proceed in one of two directions:

1. Save the image at 300 dpi (max size 10" wide and 7.5" tall). Import the image into the slide through the Insert Menu: Insert>Picture>From File. Powerpoint will embed the higher res image into the slide presentaion but will automatically downsample it when it displays the slide.

2. If method 1 produces a file which is too large, then downsize the images to 72 dpi prior to importing theminto ppt.

Regards, Murray

I have a client who needs slides scanned to make a Power Point type presentation to be used with a computer and projector.

What dpi should I use for scanning, what file type [jpeg vs tiff] and what image size do I need to end up with?

I ususally use tiff files for scanned images.
Assuming a 35mm slide is 1 3/8 in x 7/8 in or 1.375 in x .875 in
1.375 x 1200 dpi = 1650 pixels
.845 x 1200 dpi = 1050 pixels
The size you need to end up with is determined by the destination. We know this image will be shown on a computer monitor/projector so we need to know the resolution of this display device. I'm good with all the theoreticals but the details would need to be supplied by the client perhaps? If they can't, go with 1200 dpi because a desktop resolution of 1600x1200 is still considered fairly high res... I think.
http://www.projectorpoint.co.uk/Projector-Resolution.htm - will give you UXGA and other desktop res terms if the client only knows those and not the pixel counts.

You can always scan at a higher dpi of course but I wouldn't reccomend going below 1200 dpi for 35mm slides to be displayed this way. JPEG is fine as long as it's not highly compressed. In Picasa and Irfanview using a JPEG compression of 90% is usually fine and in Photoshop I recommend at least 10 (scale goes from 1 to 12) 'baseline standard' but in many cases I've found that I can get away with 8 instead of 10 for just throwing images up on a screen. It depends on the amount of fine details in the images though.

Using tiff files for this case would just create unnecessary overhead and inflated file sizes and increase the amount of time it takes to work with the images after they've been saved... of course this is just my opinion and I don't notice the extra added time until I'm dealing with hundreds to thousands of files :)