Understanding Exporting in Lightroom

[Andrewjmarino]

Hi,

I hope that it's ok to ask beginner questions here. I basically understand all of Lightroom except for getting my images out of there - exporting. I've heard and read so much "do this" "don't do that" that now I'm confused about pixels, print size, file size, resolution.
I'm mostly interested in exporting jpegs to take to a print shop. Though I also want to learn the Print Module, sending to an online service and I do maintain a work website so I need to learn for those purposes, as well.
My primary questions are related to aspect ratios; pixel size; resolution and exporting hopefully to be able to set up some user settings that I understand.

The images below are only for understanding the concepts, not meant to actually be "good" photos


1) First, since this is my first 4:3 camera (OMD EM1) I need to understand the relationship between the aspect ratio to the physical print sizes.
If I understand correctly, the common physical print sizes for 4:3 are 6×8 inches, 9×12 inches, 12×16 inches....etc. This should be the correct sizing, right?

I have to convert these to cm for where I live in Cambodia. Frankly, I don't know if the print shops here even understand the difference between 4:3 and 3:2 etc. which will be another challenge and issue into itself. They print the way they want to print, not paying attention to colors, tones, etc. Mostly, people in photographs get turned into a "white" people.

2) Here is a scenario that is confusing me. Let's say I want to take an original full-size image (4608x3456) and then, for example, I want to crop it significantly (1407x1055). The cropped size is only for conceptual understanding. The aspect ratio is the same 4:3

In both cases in Lightroom, I set the File Settings > Quality to 100
Image Sizing is unchecked and Resolution is 300 PPI - but I think if Image Sizing is unchecked, then you cannot independently change the Resolution? At least, I think that's how LR works (another question yes/no?)

Now, if I also understand correctly, to make a 6x8 inch print at 300 PPI then I actually need a file that is 1800x2400 pixels (the cropped image is only 1407x1055).
Is this going to be a problem printing???

Do I need to drop the Resolution to about 180 PPI (1080x1440) for the cropped image to print at a good "quality?"

To add to more of my confusion, I also read a forum that said LR has its own interpolating algorithm that can "upsize" the image, though there must be some sort of limit to how far it can be pushed upward.

3) What if I want to take that 1407x1055 cropped image and print it at 9x12 inches, or 12x16? Can this even be done by reducing the PPI so much and still get a good print?

4) Finally (whew), what if I have a series of 4:3 images with widely varying crop sizes. Some are full-size (example above), some medium and some cropped small like the example above. What settings will get them out of Lightroom to print at the same size and quality?

I hope my questions make sense and are clear. I might be confusing too many different things and not really understanding the concepts.

Thanks
Andrew


I have two other questions about making enlarged prints and manually cropping an image to a random size and non-normal aspect ratio and then figuring out how to get it out of LR and print it to a given size. But, I'll save those question for later

[IzzieK]

I do not have Lightroom so I cannot respond to your question, but I like your shots here, not too sharp, not too soft. I am responding to this to bump this thread up as there are many here who uses Lightroom that can teach you until you get the answer to your question right.

[pnodrog]

You could try the settings below. I have underlined in red the settings that you need to select. 95 is usual acceptable for jpeg quality. The sharpen settings will depend a bit on what type of paper you are printing on and the amount of sharpening already done in the develop module. Using the Width & Height selection will cater for the longest dimension if the ratio is not exact. Provided you leave the Don't Enlarge box unchecked the photo if needed will be enlarged to selected print size. If you enlarge too much the print quality will suffer but a 30-40% increase will probably be acceptable if you are not a pixel peeker.

If you get a high quality printer you may get better results by exporting as TIFF file and aRGB but discuss it with the printer first.

[benm]

3) What if I want to take that 1407x1055 cropped image and print it at 9x12 inches, or 12x16? Can this even be done by reducing the PPI so much and still get a good print?

4) Finally (whew), what if I have a series of 4:3 images with widely varying crop sizes. Some are full-size (example above), some medium and some cropped small like the example above. What settings will get them out of Lightroom to print at the same size and quality?

I hope my questions make sense and are clear. I might be confusing too many different things and not really understanding the concepts.

Thanks
Andrew


I have two other questions about making enlarged prints and manually cropping an image to a random size and non-normal aspect ratio and then figuring out how to get it out of LR and print it to a given size. But, I'll save those question for later

I will try to answer 3) and 4).
3) the number of dpi you need for printing depends on the printing medium. For the numbers you provided, 1407/12 = 117 dpi and 1407/16 = 88 dpi, is probably sufficient for a canvas, less so for a glossy paper.

4) always export at the highest quality settings.

For non-normal aspect ratio - the important point to keep in mind is that when you send it for printing and you don't provide any instructions the printer may crop it to fit the requested print size and that may cut off a critical part of the photo. You need to work with the printer to get the entire cropped image printed. The alternative is to add white or black bars to your cropped photo so that aspect ratio is the same as the requested print - the printer will print the entire image which includes the bars, which you then trim off.

[DanK]

This may be a lot simpler than you think.

Check with the print lab about what they want. The lab I use on the rare occasions when I don't print myself requests the largest, highest quality jpg I can give them, in sRGB. They do the resizing and output sharpening themselves. I have to crop to the right aspect ratio and, of course, edit it to my taste.

If they want you to do the resizing, then ask them what dpi setting is best for their printers.

[davidedric]

Just going back to the ppi. This has come up before, and it has nothing to do with the resolution of the final print (which is why it is ppi not dpi). It's the resolution hat the printer expects in the file, and it is normally suggested to be 240 for Epson and 300 for Canon printers, but in practice it may not be too important.

Dave

[pnodrog]

Just going back to the ppi. This has come up before, and it has nothing to do with the resolution of the final print (which is why it is ppi not dpi). It's the resolution hat the printer expects in the file, and it is normally suggested to be 240 for Epson and 300 for Canon printers, but in practice it may not be too important.

Dave

You can see Lightroom have avoided the confusion by simply calling it resolution which is exactly all it is in file form and even then it is just an entry to metadata.

[Polar01]

Dave most of the higher end Epson printers are 360 now for the past few years, Canon and Dell are 300 and your standard bookshelf printer need no more than 240.

Cheers: Allan

[jcuknz]

If we are going into the finer points as Dave #6 has mentioned that 240/300 should be based on the printer maximum capability and result from it beoing divided by a whole number [ not number and decimal points]

So you do not use 240 on a 3000 printer because it results in 12.5, better is 300 which results in 10

[Downrigger]

This has helped me. Hope it's OK to hijack now for export to web. Be nice to see your sample screen for export for viewing on web, L.Paul. I assume you do not enter dimensions plus resolution which seems so straightforward for exporting for print.

Rather, seems you would use "pixels per long edge" or "megapixels" or "pixels per inch" (or some combination) which all seem somewhat related but somehow adrift without an actual length or width, so I really have not been able to wrap my head around this yet.

For export to web I've understood lower quality is OK (say 85) and tended to set around 1000 pixels per long edge. I assume there is no sense at that point in entering anything for resolution.

And, yes, really nice images, Andrew.

[pnodrog]

This has helped me. Hope it's OK to hijack now for export to web. Be nice to see your sample screen for export for viewing on web, L.Paul. I assume you do not enter dimensions plus resolution which seems so straightforward for exporting for print.

Rather, seems you would use "pixels per long edge" or "megapixels" or "pixels per inch" (or some combination) which all seem somewhat related but somehow adrift without an actual length or width, so I really have not been able to wrap my head around this yet.

For export to web I've understood lower quality is OK (say 85) and tended to set around 1000 pixels per long edge. I assume there is no sense at that point in entering anything for resolution.

And, yes, really nice images, Andrew.

Your assumption is incorrect. The method you mention is exactly how I did it in the example posted but provided the print dimensions are in whole inches I can work happily with either dimensions or pixels.

However most of my work is with odd sizes such as 8.3cm x 5.7cm so my normal practice is in develop, to crop with a preset at that ratio and then export with dimensions set as required and at 300 ppi. I do not like multiplying by 118.1102 to convert the length in cm to the number of pixels needed to give 300ppi.

[Dave Humphries]

This has helped me. Hope it's OK to hijack now for export to web. Be nice to see your sample screen for export for viewing on web, L.Paul. I assume you do not enter dimensions plus resolution which seems so straightforward for exporting for print.

Rather, seems you would use "pixels per long edge" or "megapixels" or "pixels per inch" (or some combination) which all seem somewhat related but somehow adrift without an actual length or width, so I really have not been able to wrap my head around this yet.

For export to web I've understood lower quality is OK (say 85) and tended to set around 1000 pixels per long edge. I assume there is no sense at that point in entering anything for resolution.

And, yes, really nice images, Andrew.

Hi Mark, Andrew,

Yes, if you want to produce a picture for web viewing, forget physical dimensions, change the units (when re-sizing) to be pixels (pure and simple), this will remove dpi/ppi figures from the equation, making life much simpler.

I suggest people ignore advice to "set 72 ppi for web" use - it is irrelevant.

As I said above, set the units to pixels, then decide what resolution screen you want it to be viewable on at 100% or "1:1" - that is one monitor pixel to one image pixel.

Many monitors are 1680 x 1050, or 1920 x 1080 (w x h), laptop screens are usually rather smaller

I always suggest that since 99% of people* are viewing on a landscape oriented monitor, even when viewing portrait oriented shots, it makes sense not to exceed the pixel 'height' of the monitor, or the whole image cannot be viewed at its sharpest (1:1) without scrolling up and down, ruining the composition.

So that suggests say, 1000px height, assuming they view the picture in a Lytebox and with the browser in full screen mode (F11 on PC keyboard toggles this on/off easily).

So, regardless of the image's compositional orientation, set the height to about 1000 px and see what the width comes out to, if a 'landscape' shot, you may need to reduce the height a little to get the width within 1600px, which is essential if using TinyPic, but is a good idea anyway, so it fits those 1680 x 1050 screens without panning.

* I accept this doesn't account for smart-phone and tablet users who might rotate their devices into portrait orientation and the software will zing it up full size, but those screens are unlikely to be used for critical image viewing where sharpness is a bigger issue.

Cheers, Dave

[IzzieK]

......
For export to web I've understood lower quality is OK (say 85) and tended to set around 1000 pixels per long edge. I assume there is no sense at that point in entering anything for resolution....

I'd say the most commonly used in Photoshop for Save for the Web option is 72dpi...so if stretched, it will not be as use-able.