Tweaking a photo and saving shirnks the files size

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DoubleD
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Tweaking a photo and saving shirnks the files size

Post by DoubleD » Mon Sep 21, 2015 4:45 pm

I tried xnView and XnViewMP. I may rotate a photo or crop it and I noticed that when I save my changes the file's size is drastically reduced
2,000kb down to 600kb

Does this mean that tweaking a photo and saving it will reduce the photo's quality and characteristics. Why does the size shrink so much?


DoubleD
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Re: Tweaking a photo and saving shirnks the files size

Post by DoubleD » Mon Sep 21, 2015 8:21 pm

XnTriq wrote:Welcome to the forum, DoubleD.

If you crop a photo, image data is discarded which leads to smaller file size.
What format (JPEG, PNG, GIF, …) are we talking about?
Thanks for the welcome!!

They are .JPG files. I can see a little smaller but not this much. I just opened a file did noting to it and selected save as JPEG/JFIF). The file size went from 2093 KB down to 552 KB ?

DoubleD
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Re: Tweaking a photo and saving shirnks the files size

Post by DoubleD » Mon Sep 21, 2015 8:35 pm

Oh maybe I found it

You have to set out to best on the options "write tab" for JPEG

I'd up load an image if I knew how ...
Well I tried that and the resulting file is bigger but still much smaller that the original

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XnTriq
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Re: Tweaking a photo and saving shirnks the files size

Post by XnTriq » Mon Sep 21, 2015 8:45 pm

Unfortunately, JPEG is a very complex format and tricky to deal with.
This is where you'll find the settings for saving (and re-saving) JPEGs:
  • XnView Classic
    • File » Save As... » Options takes you to
      Tools » Options... » Read/Write » Write » JPEG
    • File » Export... » JPEG
  • XnView MP
    • File » Format settings... » Write » JPEG
    • File » Export... » JPEG
XnTriq ([url=http://newsgroup.xnview.com/viewtopic.php?p=34186#p34186]Lossless JPEG transformations[/url]) wrote:
XnTriq ([url=http://newsgroup.xnview.com/viewtopic.php?p=100082#p100082]JPEG compression as lossless as possible[/url]) wrote:
XnTriq ([url=http://newsgroup.xnview.com/viewtopic.php?p=93079#p93079]Adjust-Automatic Levels / filesize[/url]) wrote:The problem with this setting ...
  • Tools » Options » General » Read/Write » Write » JPEG » Parameters » Use estimated original quality if possible
... is that XnView only takes the compression level (“Q factor”) into account, ...
Calvin Hass ([url=http://www.impulseadventure.com/photo/jpeg-compression.html]JPEG Compression, Quality and File Size[/url] » Where does the error come from?) wrote:By far the biggest contributor to the error (ie. file size savings) in the JPEG algorithm is the quantization step. This is also the step that allows tuning by the user. A user may choose to have a slightly smaller file while preserving much of the original (ie. high quality, or low compression ratio), or a much smaller file size with less accuracy in matching the original (ie. low quality, or high compression ratio). The tuning is simply done by selecting the scaling factor to use with the quantization table.
... but ignores other criteria such as chroma sub-sampling.
Calvin Hass ([url=http://www.impulseadventure.com/photo/jpeg-compression.html]JPEG Compression, Quality and File Size[/url] » Where does the error come from?) wrote:The act of rounding the coefficients to the nearest integer results in a loss of image information (or more specifically, adds to the error). With larger quality scaling factors (ie. low image quality setting or high numbers in the quantization table), the amount of information that is truncated or discarded becomes significant. It is this stage (when combined with the Run Length Encoding that compresses the zeros) that allows for significant compression capabilities.

There are other contributors to the compression error, such as the color space conversions, but the quantization step is the most important.
See also: Save JPG At 'Original' Quality

DoubleD
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Re: Tweaking a photo and saving shirnks the files size

Post by DoubleD » Mon Sep 21, 2015 8:57 pm

DoubleD wrote:Oh maybe I found it

You have to set out to best on the options "write tab" for JPEG

I'd up load an image if I knew how ...
Well I tried that and the resulting file is bigger but still much smaller that the original


Oops I goofed - Tools, Options, Write tab, highlight/choose JPEG and setting quality top BEST actually makes the resulting file as big or even a little bigger.

OK for someone who has no clue (me) - What is a good setting for this parameter where the photo is not compromised and some space is saved?

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Re: Tweaking a photo and saving shirnks the files size

Post by XnTriq » Mon Sep 21, 2015 9:15 pm

DoubleD wrote:I'd up load an image if I knew how ...
cday's step-by-step tutorial for uploading attachments :-)
DoubleD wrote:What is a good setting for this parameter where the photo is not compromised and some space is saved?
It depends on what you're planning to do with the result. Are you going to use it in desktop publishing (e.g. MS Word), upload it to the web, send it via e-mail, or will it be an archival copy?
p127715.png
My default settings
Did you activate Use estimated original quality if possible?

DoubleD
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Re: Tweaking a photo and saving shirnks the files size

Post by DoubleD » Mon Sep 21, 2015 9:26 pm

Cool on the tutorial - I didn't see that upload tab on the bottom - Every forum is so different

Yes I did tick the estimated original quality if possible it comes close but pushing it to best gives the closest to original (for my simple test anyway).

I want to upload the photos to a private cloud where I will share to others so they can print and or make a slide show for themselves.
The printing and making a slide show I would guess the closest to the original size the better (they my crop and zoom)
If putting on a website and or maybe a web slide show then the smaller the better

I will have to play with it and maybe have two areas - one for full bore file and one for website use.

Can XnView create a slide show that I can put on a web site? - I know the question is morphing I'm sorry

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Re: Tweaking a photo and saving shirnks the files size

Post by XnTriq » Mon Sep 21, 2015 10:00 pm

DoubleD wrote:Yes I did tick the estimated original quality if possible it comes close but pushing it to best gives the closest to original (for my simple test anyway).
As mentioned in my previous post, “the problem with this setting is that XnView only takes the compression level (‘Q factor’) into account, but ignores other criteria such as chroma sub-sampling.” Both parameters have an influence on quality and file size.
DoubleD wrote:Can XnView create a slide show that I can put on a web site?
Create » Web Page... allows you to generate HTML galleries, but I don't think that any of the templates offer a built-in slideshow.
Have you tried Create » Slide Show... » Create Video..?

DoubleD
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Re: Tweaking a photo and saving shirnks the files size

Post by DoubleD » Tue Sep 22, 2015 3:48 pm

DoubleD wrote:Cool on the tutorial - I didn't see that upload tab on the bottom - Every forum is so different

Yes I did tick the estimated original quality if possible it comes close but pushing it to best gives the closest to original (for my simple test anyway).

I want to upload the photos to a private cloud where I will share to others so they can print and or make a slide show for themselves.
The printing and making a slide show I would guess the closest to the original size the better (they my crop and zoom)
If putting on a website and or maybe a web slide show then the smaller the better

I will have to play with it and maybe have two areas - one for full bore file and one for website use.

Can XnView create a slide show that I can put on a web site? - I know the question is morphing I'm sorry
I don't see the screen you pasted into this reply on XnViewMP version Version 0.72 x32 (Dec 19 2014). It is in XnView version 2.33. The file size get drastically reduced when using save as. I did find the Export setting and bumped that up to best and if I export the file the size is at lease as big or bigger.


All I see is
XV2.png

cday
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Re: Tweaking a photo and saving shirnks the files size

Post by cday » Tue Sep 22, 2015 4:49 pm

DoubleD wrote:I don't see the screen you pasted into this reply on XnViewMP version Version 0.72 x32 (Dec 19 2014).
It's well hidden in File > Format settings... , a current issue Pierre is trying to resolve.
XnViewMP_File - Format_settings....png
Sorry to intrude... :wink:

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XnTriq
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Re: Tweaking a photo and saving shirnks the files size

Post by XnTriq » Tue Sep 22, 2015 5:00 pm

Yes, my screenshot is from XnView “Classic” (v2.34).
XnTriq wrote:
This is where you'll find the settings for saving (and re-saving) JPEGs:
  • XnView Classic
    • File » Save As... » Options takes you to
      Tools » Options... » Read/Write » Write » JPEG
    • File » Export... » JPEG
  • XnView MP
    • File » Format settings... » Write » JPEG
    • File » Export... » JPEG
If cropping and/or rotating is all you're gonna do with your photos, you can avoid so-called “generation loss” by using Tools » JPEG lossless transformations.
cday wrote:Sorry to intrude... :wink:
L :mrgreen: L

DoubleD
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Re: Tweaking a photo and saving shirnks the files size

Post by DoubleD » Tue Sep 22, 2015 5:13 pm

I don't have a files, Format options or I don't know how to get to it
XV4.png

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XnTriq
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Re: Tweaking a photo and saving shirnks the files size

Post by XnTriq » Tue Sep 22, 2015 5:23 pm

DoubleD wrote:I don't have a files, Format options or I don't know how to get to it
Oh, I didn't realize that Format settings... is only available in the viewer's File menu :-|
You have to open an image to get there.

cday
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Re: Tweaking a photo and saving shirnks the files size

Post by cday » Tue Sep 22, 2015 5:24 pm

DoubleD wrote:I don't have a files, Format options or I don't know how to get to it
Hello again:
XnViewMP_File - Format_settings... _2.png

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