Lightroom Resizing for 6x4 prints

I've read a number of threads here and am still partly confused. I have a number of prints made from an old Powershot S3 that I want printing to 6x4. I know the aspect ratio of the old Powershot will be different. I intend to use Lightroom 3 and have the following questions:

• Currently I'm cropping to a 6"x4" aspect ratio and then exporting to JPEG size 6"x4". The resultant dpi is 240, 1440*960 pixels. Will this give me good quality pics?

• Another approach is to not crop and simply export to JPEG in 6"x4". What I can't work out is why the final images is what it is. Doing this it's 1280*960 so a 5.3"x4" print so I'm assuming LR tries to preserve the original aspect ratio therefore only making one edge 4" and not making the other 6"? Is this the default method to prevent stretching or skewing of photos?

• My final approach is to do a 6"x4" crop and not select a predefined export size. I'm assuming LR would output the 6"x4" but instead I'm getting a 2272*1515 image at 240 dpi. This would be 9.4"x6.3". I'm assuming I have to crop at 378 dpi here to get a 6x4 if I want to do it this way, and if so, is this better than the first way?

• Is there a better way that I'm missing?

If it was me, I'd be making them 1800 x 1200 px (300ppi) this would be for sending off to be printed by a lab.

Are you printing at home or emailing them off?

minstral wrote in post #11497269
I've read a number of threads here and am still partly confused. I have a number of prints made from an old Powershot S3 that I want printing to 6x4. I know the aspect ratio of the old Powershot will be different. I intend to use Lightroom 3 and have the following questions:

• Currently I'm cropping to a 6"x4" aspect ratio and then exporting to JPEG size 6"x4". The resultant dpi is 240, 1440*960 pixels. Will this give me good quality pics?

• Another approach is to not crop and simply export to JPEG in 6"x4". What I can't work out is why the final images is what it is. Doing this it's 1280*960 so a 5.3"x4" print so I'm assuming LR tries to preserve the original aspect ratio therefore only making one edge 4" and not making the other 6"? Is this the default method to prevent stretching or skewing of photos?

• My final approach is to do a 6"x4" crop and not select a predefined export size. I'm assuming LR would output the 6"x4" but instead I'm getting a 2272*1515 image at 240 dpi. This would be 9.4"x6.3". I'm assuming I have to crop at 378 dpi here to get a 6x4 if I want to do it this way, and if so, is this better than the first way?

• Is there a better way that I'm missing?

I'm totally new to printing and am pretty confused.

Many thanks in advance everyone.

1. Use this method. This will give you consistent results for 6x4 prints. You could increase the PPI to 300 if you want. You may or may not see a difference (I use 300 because it is easier to multiply than 240 to make sure I have the correct final size - 1800x1200 pixels).

2. When you use this method LR will limit the export to either 6" or 4". The aspect ratio of the image in this case means the 4" side is the restricted one. That is why you get less than 6" on the other side. More on this below.

3. Using this method LR is still exporting your desired aspect ratio but isn't resizing the image to 240PPI. So you get all of the pixels left after your crop. This also means an inconsistent PPI since not all of your files may be cropped to the same size, even though they may be cropped to the same aspect ratio.

Here is how I do it:

- Crop to my desired aspect ratio, in your case here 6x4.
- In the export dialog box I will set LR for pixels and use 1800x1800 (NOT 1800x1200!!!). This way I get a 6x4 @ 300 PPI for both Portrait and Landscape orientation. If you use 1800x1200 and have a mixture of portrait and landscape photos, you will get 1800x1200 for some and 800x1200 for others.
- I use 90 for my quality slider to help reduce file size slightly and see no difference in prints.

minstral wrote in post #11497269
I've read a number of threads here and am still partly confused. I have a number of prints made from an old Powershot S3 that I want printing to 6x4. I know the aspect ratio of the old Powershot will be different. I intend to use Lightroom 3 and have the following questions:

• Currently I'm cropping to a 6"x4" aspect ratio and then exporting to JPEG size 6"x4". The resultant dpi is 240, 1440*960 pixels. Will this give me good quality pics?

Yes it will. 1800x1200 (300 ppi) might be a little better, but they will be pretty close.

LR will not change the aspect ratio when exporting. It will always preserve either the original or the cropped shape.

Easier, but not better. You send the print lab all the pixels you have and let them worry about resizing. However, with method 1 you have the benefit of LR's excellent output sharpening which adjusts itself to the optimal sharpening for the image size.

OP, why not just output the image from lightroom at its native pixel dimensions. Why bother resizing just to get 300dpi. The printer will handle the scaling regardless of what dpi the image is.

Sdiver2489 wrote in post #11497733
OP, why not just output the image from lightroom at its native pixel dimensions. Why bother resizing just to get 300dpi. The printer will handle the scaling regardless of what dpi the image is.

One of the main reasons to resize yourself is to be in total control of sharpening at a particular size

Sdiver2489 wrote in post #11497733
OP, why not just output the image from lightroom at its native pixel dimensions. Why bother resizing just to get 300dpi. The printer will handle the scaling regardless of what dpi the image is.

To add to what was said above, if you have to print 50 photos, those extra worthless pixels add up for uploading.

All shots straight out of camera with your Rebel will already be in the 4x6 ratio.

Jimmer411 wrote in post #11497950
All shots straight out of camera with your Rebel will already be in the 4x6 ratio.

He's talking about a P&S camera, which is often in the 4:3 aspect ratio, meaning he needs to crop it to get a 4x6.

To the OP, as has been said, sizing it to an 1800x1200 image will give you a 4x6 print @300 ppi, and for most printers 300ppi is considered an "optimal" print size, so you can go that route -- you don't say why you are looking at 240ppi, but I imagine that it's simply because LR is setting that value as a default.

As far as just cropping to a 4x6 aspect ratio and exporting it "as is", well, that's the other approach, the printer driver will do the resizing for you. Ignore the ppi figure and any dimensions in inches -- they will be meaningless. Some printing software does a fine job of resizing and even sharpening.

So, it's up to you and how much control you want -- resized in to a given 4x6 pixel dimension for optimal sharpening (1800x1200) or let the printer software do the resizing.

Thanks for the replies so far, very useful! To answer a couple question...

Yup, sending to a lab. And 240 was the default dpi in LR.

Thanks for the detailed explanation 2photo, I think i'll go with option one. I like the control element and I can't quite get my head around option 3 and redundant pixels...i'll need to do more research. Great tip on 1800x1800 also, I do have a mix of portrait and landscape.