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JPEG Quality Estimate


You can actually query an estimate for the quality setting used to save a JPEG image.

 

In FileMaker

Set Variable [$img; Value:MBS("GMImage.NewFromContainer"; Image::InputImage)]

Set Variable [$value; Value:MBS("GMImage.GetAttribute"; $img; "JPEG-Quality")]

Show Custom Dialog ["JPEG Quality used to compress …"; $value]

Set Variable [$r; Value:MBS("GMImage.Destroy"; $img)]

Or in Xojo:

dim f as FolderItem = SpecialFolder.Desktop.Child("test.jpg")

dim g as GMImageMBS = new GMImageMBS(f)

dim s as string = g.attributeValue("JPEG-Quality")

MsgBox "JPEG Quality: "+s

GraphicsMagick lets you read various attributes including EXIF, IPTC and 8BIM metadata.

The JPEG loader in GraphicsMagick checks the JPEG settings for colorspace, orientation and quality, so the same settings can be used to save the same image again.

04 03 17 - 21:06
two comments

“ and quality, so the same settings can be used to save the same image again.”

Would that not result in a progressive worsening of the image quality? I remember people setting the JPG quality for saving to 90% (or less) to reduce image siez, and being very surprised about how their picture looked after several rounds of loading/saving.
Markus Winter - 05 03 17 - 17:42

Of course this decreases quality. But if images was saved with 90%, it uses at least 90% and not some default like 80%.
Christian Schmitz (URL) - 05 03 17 - 17:44


  
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