Whats the best way to shrink files size

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DoubleD
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Joined: Mon Jul 06, 2015 3:40 pm

Whats the best way to shrink files size

Post by DoubleD »

I'm working with 12 - 15MG JPG files. I drop the photos into Xnconvert do auto level auto contract a little sharpen and then a bloom, Then I add a bunch of text lines and a watermark.

I always wondered if the order of the actions made a difference ...

Can I use XnConvert to reduce the resulting file size and how


When I set the JPEG settings to a quality of 100 the file sizes shrink to 10 -13 MB - Not sure why they don't stay original BUT the real question is;


When I set the JPG setting to a quality of 80 the file size shrinks tremendously 1.3 to 1.5 MB Is this the right way to reduce files sizes or is there a better way - I'm posting these files to a facebook sports group in a photo album.
cday
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Re: Whats the best way to shrink files size

Post by cday »

DoubleD wrote: Thu Sep 15, 2022 11:16 pm I'm working with 12 - 15MG JPG files. I drop the photos into Xnconvert do auto level auto contract a little sharpen and then a bloom, Then I add a bunch of text lines and a watermark.

I always wondered if the order of the actions made a difference ...
Not as far as I know, except possibly very slightly.

Can I use XnConvert to reduce the resulting file size and how?
Yes, the various save settings selected determine file size, in XnConvert those are set on the Output tab.

When I set the JPEG settings to a quality of 100 the file sizes shrink to 10 -13 MB - Not sure why they don't stay original BUT the real question is:

When I set the JPG setting to a quality of 80 the file size shrinks tremendously 1.3 to 1.5 MB Is this the right way to reduce files sizes or is there a better way - I'm posting these files to a facebook sports group in a photo album.
The selected quality value is the main setting that affects file size, for any normal use the maximum value of 100 is higher than is needed, and will result in a substantially larger file. When file size matters, it is normally best to test reducing values until the lowest acceptable quality is reached, leaving a little in reserve as images can vary. The type of image content and the use to which the images will be put will normally be relevant. In my experience images with large pixel dimensions can often be saved satisfactorily with surprisingly low quality values.

For images to be placed online on a site like Facebook, I would think that relatively low quality values would be satisfactory. It might when practical be worth keeping a copy of the original images in case they are needed later, though.

Note that with a tabbed viewer such as XnView MP, you can easily compare side-by-side copies of an image saved with different settings, and if you wish zoomed-in views if you can figure out the zoom and lock zoom settings.
DoubleD
Posts: 65
Joined: Mon Jul 06, 2015 3:40 pm

Re: Whats the best way to shrink files size

Post by DoubleD »

cday wrote: Fri Sep 16, 2022 5:50 am
For images to be placed online on a site like Facebook, I would think that relatively low quality values would be satisfactory. It might when practical be worth keeping a copy of the original images in case they are needed later, though.

Note that with a tabbed viewer such as XnView MP, you can easily compare side-by-side copies of an image saved with different settings, and if you wish zoomed-in views if you can figure out the zoom and lock zoom settings.

Thanks for the reply - Sounds like this is the correct way

I guess finding what is acceptable is trial and error; set quality to 30% and have a look - my cloudy sky looked haloed 50 was OK and 70-80 seemed the best

So the quality is directly related to size. I wish there was a reduce filesize option kind of like in lightroom
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helmut
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Re: Whats the best way to shrink files size

Post by helmut »

DoubleD wrote: Thu Sep 15, 2022 11:16 pm.. Is this the right way to reduce files sizes or is there a better way - I'm posting these files to a facebook sports group in a photo album.
One way to reduce files size is reducing JPEG quality and thus loosing image information and details. A second way is to reduce size of the image. I'm not familiar with photo albums in facebook but my guess is that your image size (width x height in pixels) can be reduced. Have a look at some few images in the in photo album and check their image dimensions (width x height in pixels).

Notes:
- Reducing image size/dimensions as suggested above can be combined with saving with lower JPEG quality.
- For reducing image size and saving with quality loss you can use batch conversion of XnView. (EDIT: You had posted in XnConvert forum so this note is superfluous. ;) )
- Make sure to keep your original files. ;)

Related topic:
- How to reduce an image's file size?
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XnTriq
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Re: Whats the best way to shrink files size

Post by XnTriq »

DoubleD wrote: Thu Sep 15, 2022 11:16 pmWhen I set the JPEG settings to a quality of 100 the file sizes shrink to 10 -13 MB - Not sure why they don't stay original BUT the real question is;


When I set the JPG setting to a quality of 80 the file size shrinks tremendously 1.3 to 1.5 MB Is this the right way to reduce files sizes or is there a better way - I'm posting these files to a facebook sports group in a photo album.
You can reduce the file size without loss of image quality by optimizing the Huffman table and removing the metadata.

Not all options are included in batch mode, though:
  • XnView MP: ToolsMetadataClean…
    • Optimize Huffman table
    • Remove
      • Comment
      • EXIF
        • EXIF thumbnail
        • GPS
      • IPTC-IIM
      • ICC profile
      • All other 'APP' markers
  • XnConvert: Add actionImageClean metadata
    • Comment
    • EXIF
    • XMP
    • EXIF thumbnail
    • IPTC
    • ICC profile
Some cameras create JPEGs that have not only small thumbnails embedded in them, but also fairly big “previews”.

Related topic: Cleaning metadata affecting image quality?