# Viewing file size in mac



## Maria Falconer (Aug 6, 2017)

Hi all 
I have a problem that I hope someone can help with. I've been using LR for years - since V1. I'm not an expert but comfortable with the programme. I am a professional photographer and two days ago I edited my RAW files on my new laptop (MacBook pro) and exported the files as .jpgs 10" longest side @300 ppi. When I look at the file in the finder window however it is telling me that it's only 229kb - when I open it in photoshop it appears to be the full size. The client returned the files saying they were low res so out of desperation I exported the catalogue to my old MacBook air and again exported as .jpg's 10" @300 ppi. This time they showed in the finder as 2.8Mb. So today when I got home I loaded both files onto my desktop and low and behold they both appear to be identical in photoshop but in finder window they are completely different sizes. 


 

 I've attached both files here.
Is it possible that the finder is reading the size of the thumbnail - even though when click on info it still tells me the same? Or is there some other devilment at work here  Completely flummoxed and any ideas appreciated.


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## Johan Elzenga (Aug 6, 2017)

The file size on disk is determined by the level of jpeg-compression. The file size that Photoshop shows is the uncompressed size. Apparently you used different levels of compression (quality setting) in the export dialog, but often that difference is not detectable to the human eye.


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## Maria Falconer (Aug 6, 2017)

I t


Maria Falconer said:


> Hi all
> I have a problem that I hope someone can help with. I've been using LR for years - since V1. I'm not an expert but comfortable with the programme. I am a professional photographer and two days ago I edited my RAW files on my new laptop (MacBook pro) and exported the files as .jpgs 10" longest side @300 ppi. When I look at the file in the finder window however it is telling me that it's only 229kb - when I open it in photoshop it appears to be the full size. The client returned the files saying they were low res so out of desperation I exported the catalogue to my old MacBook air and again exported as .jpg's 10" @300 ppi. This time they showed in the finder as 2.8Mb. So today when I got home I loaded both files onto my desktop and low and behold they both appear to be identical in photoshop but in finder window they are completely different sizes. View attachment 9666 View attachment 9667 I've attached both files here.
> Is it possible that the finder is reading the size of the thumbnail - even though when click on info it still tells me the same? Or is there some other devilment at work here  Completely flummoxed and any ideas appreciated.


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## Maria Falconer (Aug 6, 2017)

Johan - you are correct!! Thanks so much. When I noticed that the quality slider was down I did a test with it back to 100 but in the chaos and panic I think I actually then looked at the wrong file, leading me to believe that that wasn't the issue. I've just done another test however and it appears to be the case - thanks so muchh for help.


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## Maria Falconer (Aug 6, 2017)

Johan - could I ask then.....presumably not good to use this kind of compression because there will be loss of quality, even though photoshop shows the same number of pixels?


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## Hal P Anderson (Aug 6, 2017)

Maria,
Here's the canonical article on JPEG compression:
An Analysis of Lightroom JPEG Export Quality Settings


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## Maria Falconer (Aug 6, 2017)

thanks Hal - most interesting


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