I am scanning some photos, mostly 4X6 and will be showing them on a projector. The suggested resolution for photos on my scanner is 150dpi. How will that look when blown up onto a 12 foot screen? Unfortunately, I don't have access to the projector until the day of the slideshow.
I tried scanning at higher resolutions but anything past 300x300 is very slow. It would take me days to scan all the photos.
When I display on my 13 inch screen, the 150dpi photos look pretty good.
A 6x4" image at 150 ppi blown up to a 120" x 80" will have 7.5 pixels per inch.
But there is not much you can do about that.
Make your final images at the maximum resolution of the projector.
It should not take long to scan a 4x6.
My five year old USB2 Epson does a preview in 10 seconds, a 300 ppi scan in 30 seconds and a 600 ppi scan in 84 seconds.
I could drone on about this for days, but In a nutshell:
You'll want to scan your 4x6 prints at a minimum 300ppi. Scan as TIFFs / 8-bit / sRGB. These will be 6MB files.
Tweak exposures, remove dust etc in PS. Then sharpen the hell out of them...depending on original focus, try 140/1.2/8. If you want a smaller file size, save as Jpeg (with the least compression). You'll now have 2MB files that should "blow up real good", as John Candy used to say.
Don't scan directly to Jpeg – they'll be too soft.
I could drone on about this for days, but In a nutshell:
You'll want to scan your 4x6 prints at a minimum 300ppi. Scan as TIFFs / 8-bit / sRGB. These will be 6MB files.
Tweak exposures, remove dust etc in PS. Then sharpen the hell out of them...depending on original focus, try 140/1.2/8. If you want a smaller file size, save as Jpeg (with the least compression). You'll now have 2MB files that should "blow up real good", as John Candy used to say.
Don't scan directly to Jpeg – they'll be too soft.
ScanMan, can you clarify what the 140/1.2/8 means?
Also, to HHK, whatever you do, once you scan your images; title that folder as original scans, then duplicate it and work on the duplicate images. This is a fail safe in case you edit an image incorrectly - you'll still have the original to use to save rescanning.
I could drone on about this for days, but In a nutshell:
You'll want to scan your 4x6 prints at a minimum 300ppi. Scan as TIFFs / 8-bit / sRGB. These will be 6MB files.
Tweak exposures, remove dust etc in PS. Then sharpen the hell out of them...depending on original focus, try 140/1.2/8. If you want a smaller file size, save as Jpeg (with the least compression). You'll now have 2MB files that should "blow up real good", as John Candy used to say.
Don't scan directly to Jpeg – they'll be too soft.
Sorry, I can't agree for the purpose stated.
The OP is going to be using a projector -- presumably they mean a digital video projection unit. The resolution of these units is screen resolution -- usually somewhere between 800x600 and 1280 x 1024 pixels. That's it.
The size of the projected image (12 foot) has nothing at all to do with having extra resolution available in the image file to "blow up" large. It is a function of the distance of the screen from the projector. The image being displayed is still limited to the resolution put out by the projector.
Thanks for all the advice. Thinking about this logically, I think what matters here is the size of the original photo. Ideally, I want to display every photo at approximately the same size. That being the case, if the photo is 4x6 and I scan at 150dpi, it's going to look fine on a 1024x768 screen resolution. However, I have a couple of passport sized photos and here, I can see I have to use a higher dpi to capture and display a larger final image.
With regard to the size of the image being displayed, 12 feet or 2 feet, it's not really going to make a difference since I am just displaying the resolution from the screen (projector) - as CanadaRAM states.
Also, if the audience is a good distance away, it's really not going to matter. The brain and eyes should sufficiently blur the image so that any jaggedness just goes away.
All this dpi stuff is very confusing. Did some reading on the web and it leaves my head spinning.
Thanks for all the advice. Thinking about this logically, I think what matters here is the size of the original photo. Ideally, I want to display every photo at approximately the same size. That being the case, if the photo is 4x6 and I scan at 150dpi, it's going to look fine on a 1024x768 screen resolution. However, I have a couple of passport sized photos and here, I can see I have to use a higher dpi to capture and display a larger final image.
With regard to the size of the image being displayed, 12 feet or 2 feet, it's not really going to make a difference since I am just displaying the resolution from the screen (projector) - as CanadaRAM states.
Also, if the audience is a good distance away, it's really not going to matter. The brain and eyes should sufficiently blur the image so that any jaggedness just goes away.
All this dpi stuff is very confusing. Did some reading on the web and it leaves my head spinning.
Yes, you are right: Scan the originals with sufficiently high resolution so that you end up with about 1.5 to 2x the pixel size of the desired output and save it. You'll have to do the math depending on the original size and the desired output size. Don't worry to much about DPI, think in terms of the H & W in pixels.
Do your image cropping, colour adjustment and touch ups on the larger file, except NOT sharpening (sharpening should only be done at the final file size / target resolution after all other edits are done). Then size the file down to the target size for your presentation and finally apply sharpening to suit. DO NOT go overboard on sharpening or you will get ugly halos around things.
Place the finished file in the presentation software at a 1:1 size - do not resize the picture with the presentation software -- your graphics program will do a better job of interpolation than the presentation software will, and the presentation will run smoother if the software isn't resizing on the fly.
Since I hate to do scanning, I prefer to scan slowly at a very high resolution -- the maximum optical my scanner can do. I then use DigitalICE or Photoshop to clean up the image, and save in a lossless format. From that file, it's easy to create a low-res, web-friendly JPG that is very small in file size.
This is obviously not best done on a tight deadline, but ensures that you will only ever have to scan the image ONCE.
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