dmr

I am preparing a series of about
100 photos in Lightroom slideshow to be presented on line on both small mobile devices and computers and possibly a projector screen. How should the photos be saved and exported so that they fit on each device ?Thank you all in advance for your suggestions.

CHG_CANON Loc: the Windy City

Yes, size matters a ton. Not so much for 1-off images, but collections of images create situations where the resulting presentation file is next to impossible to share. Determine the 'page size' of each slide in the presentation and create image files that match to the dimensions of the image within that page size. Use a lower JPEG quality too.

The LR Export Dialog is very useful for this effort, Recommended resizing parameters for digital images

cameraf4 Loc: Delaware

Great link, Paul.

burkphoto Loc: High Point, NC

If you make it a VIDEO, it can be shared via YouTube or Vimeo. Then you can quit worrying about file size.

I use iMovie. It came free with every Mac since 2000 or so. If you’re a Win10 user, Premiere Elements can do it.

With video, you can pan and zoom into your images. Apple calls that the Ken Burns Effect. For that reason, do not downsample (reduce the pixel dimensions of) your image, and do use the original file size. The software will convert every frame of video to the right size in both respects.

Aspect ratio is 16:9.
HDTV is 1920x1080 pixels.
4K video is 3840x2160 pixels.

I do “pad with canvas” to make every image start as 16:9. So whether my original is 4:3, 3:4, 1:1, 10:8, 8:10, 3:2, or 2:3... or some other shape, I add pixels on two sides to make it 16:9. Then I can show the whole original crop, if desired, before zooming into it and panning.

10 quality in Photoshop, or 85% quality in some apps, is fine. There is no need to compress further, because the video editing software does that.

A key advantage of video is that you can add titling, dissolves, special effects, sound, video clips... nearly any effect Ken Burns does in his films for PBS. Timing is controlled to 1/30 second, if desired.

via the lens Loc: Northern California, near Yosemite NP

If you are using the images directly from within LR and making a slideshow that you are going to export you do not need to do any size conversion to your images in the LR slideshow. You simply create a collect, arrange the images as you desire, and set the slideshow parameters. When you export the slideshow using the button at the bottom of the slide show the software will ask you how big you want the slideshow to be and that is where the size conversion automatically takes place. You can save it in different sizes.

dmr

Thank you all for the valuable information..How does small,medium,large translate into screen size? I do not know the viewer’s device..or is it the ratio that is important?(3:2 or 10:8 etc)

CHG_CANON Loc: the Windy City

Small, medium, large what?

For mobile devices, you might assume 16:9.

rond-photography Loc: Connecticut

I have submitted photos to club competitions where the stipulation was "save as Jpeg 7 inches long on long side". Thus you would be submitting, basically, 5X7's. The entries were projected onto a large screen for the judges to view and I could not see any degradation of my or anyone else's photo. I can't explain why a 5X7 projects well, but it does.

I have created Power Point presentations and have used even smaller images successfully, thus keeping the overall presentation a reasonable file size.

via the lens Loc: Northern California, near Yosemite NP

As long as you are sending a file that has a reasonable file size what someone sees on the screen should not be an issue. Screen resolution is a completely different topic that people will "take off on" with opinions. If you check the actual file size, which could be in KB or MB, and it's around or over 1000KB there most likely will not be a problem. Normally, sending a 1MB or 2 MB file size is standard for competitions and some will take up to a 4MB or 5MB file. The file size will depend on the final sizing of the image file.

SuperflyTNT Loc: Manassas VA

That’s kind of strange that they specify a physical size for a digital entry. Every competition I’ve entered requested a maximum and sometimes minimum pixel dimensions. 7” can mean very different sizes dependent on the DPI. 7” at 300dpi would be 2100 pixels wide while 150dpi would only give 1050 pixels wide.

burkphoto Loc: High Point, NC

"Save as Jpeg 7 inches long on long side" has no meaning! Zero, zip, nada. The only measure that makes any sense is the image dimensions in PIXELS.

Most labs want at least 240 pixels per printed inch of output at a size of 8x10 inches, which would be 1920 by 2400 pixels. For a 5x7, you need about 300 PPI, so 1500 by 2100 pixels. The important things to remember about resolutions:

1) The assumption is that these pixels are real, original, processed sensor data, as created by the camera processor or post-processing software. In other words, not *enlarged* via interpolation (interpolation creates fake pixels to make an image bigger. In doing so, it reduces the actual resolution of the image).

MORE pixels per inch are needed for smaller prints. FEWER pixels per inch are needed for larger prints. I know that seems counter-intuitive, but it's a fact. A 20x16 made at 180 pixels per inch is perfectly acceptable in all but the most ridiculous of pixel peeping situations.

Think about that. A 1920x1080 image meets HDTV specifications. If you display that image on your 55" or larger TV, and view it from six feet away, it seems quite sharp, clear, and detailed. Yet a print from it at standard 240 PPI lab resolution would be around 8x4.5 INCHES. Why? VIEWING DISTANCE.

The normal viewing distance for a print or digital monitor image is between 1.0 and 1.5 times the diagonal dimension of that image. Now, if you're the usual camera club judge, you PIXEL PEEP. You want 300 PPI, even if the print is 40x30 inches! However, for maximum photographic resolution when viewing a 5x7 section of a 40x30 from nine INCHES, that would require a 12,000 by 9,000 pixel overall image. That's 108 megapixels! Very few cameras can come close to recording that many pixels, so we will certainly accept some amount of interpolation, and tell the judge to go sit in a corner and find the pixels on the wall.

DO NOT confuse PPI and dpi. Pixels are numbers. Dots are physical spots of density, either recorded by a sensor, or laid down on paper by some kind of printing process.

Pixels do not have dimensions. They are simply RGB values representing colors of light. We can reproduce a pixel with a dot — or multiple dots — of any size.

Dots DO have dimensions, as in recording 300 dpi on a flatbed scanner, or printing at 600dpi on a mini-lab silver halide printer, or printing 2880x1440 dpi on an Epson inkjet printer.

How does all this relate to file size? Really, it does not. FILE size can be directly related to pixel dimensions, as in an uncompressed TIFF file or a generic bitmap file. But the moment you introduce some sort of compression scheme, as is used for some TIFF files and all JPEG files, it doesn't relate well, or at all! I can make a 2000x3000 pixel image into a 6 MB uncompressed TIFF, or a 1.2 MB high quality JPEG, or a 64 KB low quality JPEG.

So yes, FILE size matters, but it is not usually the most important measure of image quality or enlarge-ability. THAT would be pixel dimensions.

I know this topic confuses the hell out of lots of people. It confused me, 30 years ago. Only by working with actual images, talking to Kodak technical sales reps, making lots of prints in a pro lab, and showing them to focus groups, did I come to understand it.

I hope this helps...

via the lens Loc: Northern California, near Yosemite NP

The easy answer is read what the pop up box says upon export, LR makes it very clear as to what size to export at when you use the Export Video button there is text that tells you what that size will work for. The highest resolution it will export in is 1080 so that is what you would use for a slide show that will be projected. While it's good to know all that other stuff this is all you need to know when using the LR slideshow module. Example of the Export Video popup box here:

(Download)

nathanweddings

size ALWAYS matters!!!!

photogeneralist Loc: Lopez Island Washington State

Apple's Mail APP gives the sender the option of file size for sending their attached photos. Small medium large and full size. I found that sending a file full size produced wails of discontent since the photo area is much larger than the screen size of the recipient's computer. Medium size seems to work for my photo club picture sharing (if the lack of complaints about file size is any indication)
I don't know if this answer is to the same question the OP has posed to the hogs. Hope it's some use to someone.