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03-25-2019, 05:20 PM   #1
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Jagged lines appear when downsizing.

I'm not very tech savvy and cannot figure this out. When I view the RAW image on my computer monitor at full size it all looks sharp. But when I convert to jpeg and reduce file size in order to upload to websites straight lines take on a jagged appearance. In this instance the white numbers and letters on the boats show it the most. I've tried sharpening the RAW image. Sharpening Raw then sharpened again after reducing file size and changing to jpeg. And pretty much any other combination I can think of. Any helpful suggestions will be greatly appreciated. Thank you.


03-25-2019, 06:09 PM   #2
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QuoteOriginally posted by DW58 Quote
I'm not very tech savvy and cannot figure this out. When I view the RAW image on my computer monitor at full size it all looks sharp. But when I convert to jpeg and reduce file size in order to upload to websites straight lines take on a jagged appearance. In this instance the white numbers and letters on the boats show it the most. I've tried sharpening the RAW image. Sharpening Raw then sharpened again after reducing file size and changing to jpeg. And pretty much any other combination I can think of. Any helpful suggestions will be greatly appreciated. Thank you.
What program are you using?

Also, given that sensors are inherently sharp these days, additional sharpening in post can backfire (and it certainly has in this case).

I would start by dialing down the sharpening first, and see if that helps.

If not, see if you can change the image scaling algorithm to either bilinear or bicubic "smoother" (these are the terms Photoshop uses, options may vary in other software).

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03-25-2019, 06:36 PM - 2 Likes   #3
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Your raw converter will (or should be) applying some "capture" sharpening to the raw image when you open it in your editor. Leave the settings at their default value for this. Do not apply any more sharpening to the image until after you have downsized it. Then you can apply some "output sharpening".

What is the converter and what iare the sharpening tools you are using?
03-25-2019, 07:02 PM   #4
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QuoteOriginally posted by Adam Quote
What program are you using?

Also, given that sensors are inherently sharp these days, additional sharpening in post can backfire (and it certainly has in this case).

I would start by dialing down the sharpening first, and see if that helps.

If not, see if you can change the image scaling algorithm to either bilinear or bicubic "smoother" (these are the terms Photoshop uses, options may vary in other software).
I'm using ON1 Photo RAW 2019. It has a lot of Pentax lenses in its data base, has more bells and whistles than I'LL ever figure out how to use, and the price was right. Also, because I use Pentax cameras and lenses I obviously have a propensity to lean away from the norm. Your suggestion to " see if you can change the image scaling algorithm to either bilinear or bicubic "smoother" is Greek to me. But I appreciate the advice and will look into this.

I understand that over sharpening is not a good thing. What exactly are you talking about when you say "it certainly has in this case." What are the tell tale signs of over sharpening you see here?

Thanks Adam. This is exactly the help I need. Exact words and phrases of what I should be looking for. I watch tutorials, I download PDF how to's, etc, etc. I guess what I am needing is a glossary to understand phrases like "scaling algorithm to either bilinear or bicubic..."

I appreciate your help and I'll keep plugging away.

03-25-2019, 07:06 PM   #5
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QuoteOriginally posted by pschlute Quote
Your raw converter will (or should be) applying some "capture" sharpening to the raw image when you open it in your editor. Leave the settings at their default value for this. Do not apply any more sharpening to the image until after you have downsized it. Then you can apply some "output sharpening".

What is the converter and what iare the sharpening tools you are using?
Yeah I'm beginning to understand that OVER sharpening has been my problem. Thanks for your input. It's very much needed and appreciated.
03-25-2019, 07:07 PM - 1 Like   #6
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QuoteOriginally posted by DW58 Quote
What are the tell tale signs of over sharpening you see here?
The lines in the pic have a type of glow to them, which alongside the aliasing (jagged edges), is a common result of over-sharpening.

QuoteOriginally posted by DW58 Quote
"scaling algorithm to either bilinear or bicubic..."
Usually this would be found in a dropdown when scaling or exporting the image. Not sure if or where ON1 has it, though.

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03-25-2019, 07:13 PM   #7
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QuoteOriginally posted by Adam Quote
The lines in the pic have a type of glow to them, which alongside the aliasing (jagged edges), is a common result of over-sharpening.



Usually this would be found in a dropdown when scaling or exporting the image. Not sure if or where ON1 has it, though.
Thanks Adam. You'd probably be surprised at just how much these two sentences help. I think I've always had a little trouble with this but I've really noticed it since I've been using the K-1II. Not a surprise.

Last edited by DW58; 03-25-2019 at 07:29 PM.
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