Exporting to jpeg - quality slider and resolution
When I export to a jpeg file format, and choose 100 (%?) on the quality slider, the resulting file metadata has a resolution of 300 dpi,and say a file size of 4.54mb. If I drop the slider down to 50, then the resulting file resolution is still 300ppi, but the file size is 140kb. I am guessing that this is simply playing with compression? The image quality doesn't seem too bad. Note that I cannot see resolution in the metadata when viewing in Bridge - had to use a third party program online.
Like others I wish to post images to web pages at 72ppi, which helps a) bring down file size, and b) discourage people from downloading and printing for wall prints etc.
Is the 50% version doing this, or is it still a reasonably high quality to print. As others have stated in other posts I am not interested in exporting as a Tiff - no good to post to web.
Thanks
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Hi Steve,
The printability of the photo will depend on the Quality slider as well as the physical size (Width and Height). For example, I usually export photos for Facebook with a measurement of no more than 1200px on the long edge. It limits the size it can be printed, and it also conforms with Facebooks' recommendations for image uploads. (More on that here: https://www.facebook.com/help/266520536764594?helpref=related )
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The DPI in the metadata itself is a completely meaningless value. It once was used by DTP programs to determine the initial size of the opened image in relation to the document, even back then it was just a suggestion that the user could override. Today only the pixel dimensions are important. More important would be to show the file size before exporting because many sites have (sensible) upload limits determined by some pixel dimensions (as in “longest size not larger than 1200 pixel”) and a maximum file size (as in “file smaller than 500 kib”) - then you’d want to select the best quality for your export within that set of constraints. Most (I can’t remember one that doesn’t, even GIMP does) image editors show the file size on the basis of the current settings before you trigger the final export - with Luminar being the exception, here you have to blindly set a quality and if the file is too small you have to reexport with higher quality, if it’s too big, same but with lower quality...
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Thanks KG.. a good explanation. I limit the dimensions on the longest side to either 1000 or 2048 depending on where I am posting. Usually limit the size of the file by setting at 72ppi. Or file size can be set (or limited) if I export using Lightroom export.
Eventually I hope to break away fully from Adobe products and Luminar 2018 has been a good start. Lets hope the development promised continues. The quality slider is very hit and miss but I guess better than nothing.
Thanks once again.
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Just saw this and noted in the intial post that Steve opted to chose 100 percent quality for export. This is not really required, since there is no difference in visab le quality between 85/86 percent and 100 percent. This is why many/most tools have this (85 %) as a standard qualtity. IF you choose 100percent only file size will increase dramatically, but quality does not.
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Thanks Manfred...I have been exporting at around 65% for web and have been happy with the file size and the quality.
These days if someone wants your image there is not much you can do about it, especially with the image resizing software now available eg Topaz Labs AI Gigapixel. So I stick with a lower percentage and just vary the image dimensions as needed. Cheers
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