Export size of photos from Lightroom

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@Yvonne254490371wg0 wrote:

 I realize that size is changed upon cropping (which I do alot of) but quality should not change.  

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Are you saying that the quality is too low even if there are enough pixels in the image to meet the resolution requirements of the print? If that’s what’s happening, then the probable cause is that the JPEG compression quality is set too low.

Because if your 10.5 MB file will export at 786 KB JPEG at you set the JPEG Quality level to less than around 70, then the answer is to increase the Quality level until the visual quality is sufficient. Not the file size, but the visual quality. That 10MB raw file could export to a few hundred KB to several MB depending on how you set the JPEG quality level.

Just keep in mind that beyond a JPEG quality level of 85, the improvement in visual quality becomes harder to notice, but the file size goes up a lot more. That’s why many photo print services pros advise against setting JPEG Quality to 100.

And I have to agree with everyone else — you have got to stop equating file size with quality. Because if you have for example a 10MB file, how good that looks depends on the format and compression settings used, and that 10MB could also be reached using a wide combination of resolutions and pixel dimensions. 10MB coiuld be an awful-looking full page TIFF image, or a pristine looking JPEG image that takes up way more storage space than it should. The file size means nothing by itself…that is why everyone is asking for more details. It is that additional info — the real specs of the image — that will help answer the question. Since file size alone is not a reliable measure of quality.

You may not like the answers here, but the people answering are very experienced and knowledgeable. They are all just trying to help, and they know what they are talking about.

These points have already been mentioned but getting good quality prints from digital images is trivial. There are only a few rules:

• Export to the correct resolution: a 5x7 print should be done from an image that is scaled to 1500x2100 pixels typically - i.e. a pixel resolution of 300 pixels per inch. Just scale this for larger sizes.
• Use output sharpening at the correct resolution - This presupposes you are scaling per above but it is essential.
• Use the correct color space - if your printer supplies profiles and they know what they are doing, use those, otherwise stick to known spaces such as sRGB or adobeRGB.
• When using jpeg files, make sure to use high enough quality settings. Typically 77-85% is more than enough and there is no gain in print quality above that but you usually don't want to go below. See http://regex.info/blog/lightroom-goodies/jpeg-quality for a great analysis of this.

You should absolutely ignore filesizes as mentioned already. With jpeg, the size depends on the complexity of the image as well as the quality setting. Did a quick test and a very complex landscape image with lots of detail scaled to 5x7 and quality 85 will be around 5 MB with these settings. A flower image with large bokeh out of focus areas will come in at 800kb. Both will print perfectly.

After perusing the community for posts about export file size from Lightroom this is what I have gleaned. People who care about the quality of their photos are complaining that such quality is impaired when exporting from Lightroom. This is true because photo printing services come back at me about some of my photos not having enough pixelation to print. When I look back at the original in Lightroom, it is fine for instance a 10.5 mb file will export at 786 KB which is unacceptable to print even at 5x7 let alone 8x10. I realize that size is changed upon cropping (which I do alot of) but quality should not change.

I think what you have "gleaned" is completely wrong. So a couple of points:

1. If you are going to print the image, you need enough pixels. For example: if you are going to print a 4x6 inch print at 300 pixels per inch (ppi), then you need an export that is 1200 x 1800 pixels (or larger). That is completely under your control.
2. The file size is not a relevant indicator of quality. A file that is 1MB or a file that is 5MB may have roughly equal quality. The best way to judge quality is to LOOK AT the image yourself. Looking at file size simply tells you nothing. If you have enough pixels you will be able to print, and the quality of the print will be as good as it can be.
3. So in your example, we need to know the pixels (width and height) of the image and how large (in inches) you will be printing. Telling us 786KB is completely irrelevant and tells us nothing.

Bottom line: getting high quality prints from Lightroom Classic not only is possible, but by following the proper procedures settings you shouldn't have the slightest problem.

Digital file volume, whether it is expressed in KB, MB or GB, is not relevant for determining whether an image is suitable for printing at a particular size. What is important is the number of pixels along the sides that are available for each inch of print. Generally, the commercial machines are designed to work best when fed 300 pixels per inch and the caring/fussy photographer will submit his work with those dimensions. E.g., for an 8x10 ideally send 2400 x 3000 pixels. But the printer operators are fairly liberal in their demands because their intake software can resize the image to the needed 300 ppi. However, all resizing does have a price in quality and I imagine they would be reluctent to accept less than 150 ppi. Another factor that comes into play is that the larger the print, the greater the viewing distance and the harder it is to judge quality. Thus, for large wall-hanging prints they might accept 100 ppi.

If because of a small native size or extensive cropping, you have too few pixels, I believe it is better to use Lightroom's Export resizing than to leave it to the lab.

Work in Pixels! Figure out the size for the print you desire, then the number of pixels per inch and that's what you should export. 

You want a 10" print and your lab wants 300 pixels per inch for their printer, you simply export at 3000 pixels along that axis. 

Of course, you have to ask/find out what the lab asks for in terms of PPI and supply that/ 

Before you will get any help at all you need to provide INFO about your images you are exporting.  

What camera took these images?

How much are you cropping?   What is the pixel dimensions of a typical cropped image you are trying to export?