JPEG compression not working when saving documents

[marklucas]

Using PS 2020, on MacBookPro. When saving PS images to JPEG, the compression feature is not reducing file sizes properly. Look at this screenshot, JPEG op set to zero, but displayed file size is huge. Anyone else experiencing this bug? 

[Test Screen Name]

Not that huge. What is the image size in pixels, please?

[JJMack]

Some times there is a lot of old Meta Data that is not needed. Try this script to delete it.

function deleteDocumentAncestorsMetadata() {  
    whatApp = String(app.name);//String version of the app name  
    if(whatApp.search("Photoshop") > 0)  { //Check for photoshop specifically, or this will cause errors  
        //Function Scrubs Document Ancestors from Files  
        if(!documents.length) {  
        alert("There are no open documents. Please open a file to run this script.")  
        return;   
        }  
        if (ExternalObject.AdobeXMPScript == undefined) ExternalObject.AdobeXMPScript = new ExternalObject("lib:AdobeXMPScript");   
        var xmp = new XMPMeta( activeDocument.xmpMetadata.rawData);   
        // Begone foul Document Ancestors!  
            xmp.deleteProperty(XMPConst.NS_PHOTOSHOP, "DocumentAncestors");  
            app.activeDocument.xmpMetadata.rawData = xmp.serialize();  
         }  
}  
//Now run the function to remove the document ancestors  
deleteDocumentAncestorsMetadata(); 

[marklucas]

JJ: thanks, and sorry, not a geek, so just exactly HOW do I do this?

[marklucas]

200x200px @ 300dpi

Compare image quality settings:
12 Max = 375K
0 Low = 338K
THAT’s a problem!

[cid:image001.png@01D6715A.4BDA95A0][cid:image002.png@01D6715A.4BDA95A0]

[marklucas]

200x200px @ 300dpi

Compare image quality settings:

12 Max = 375K

0 Low = 338K

THAT’s a problem!

[Test Screen Name]

These numbers do seem to show it may be the metadata thing. I wonder, is this a file you edit again and again and again, pasting or placing new layers or graphics and saving a new copy? Each time you do that, the file grows.

[marklucas]

Indeed I do multiple saves, using it as a template, but I delete each new imported image after saving it. Seems like there should be some automatic cache or metadata clearing feature here. 

[Test Screen Name]

I agree, there should be some clean up when the imported image is deleted. But there isn't, so far as I know.

[D Fosse]

The problem is not the image itself, but excessive metadata in the file. This can happen with files from unknown sources that have been copy/pasted a huge number of times. Each paste leaves a record in metadata. This can sometimes accumulate to astonishing sizes.

If you don't want to get into scripts, a much easier way is to use Export or Save For Web. Both will strip out metadata and solve the problem.

[marklucas]

Does Export retain DPI? Because Save For Web does not.

[macsmithscurry]

Thanks. Exporting seems to clear the problem.

[Hans Petter33680451pqg5]

thanks for this🥳 saved my day

[Stephen Marsh]

More here:

https://prepression.blogspot.com/2017/06/metadata-bloat-photoshopdocumentancestors.html