How do I get a scaled down photo to look sharp against one that's not?

iggy · **Posted:** Sat Jul 16, 2016 6:44 pm **(#1)**

GIMP Version: 2.8.14
Operating System: Linux
GIMP Experience: New User

I want to have this couple running along the railroad tracks. I had to scale down the photo of the couple so they wouldn't look like giants but when I did (see the .xcf file) the couple looks totally blurry. (I know there are rough edges. I just threw it in there--but the blurriness is still evident.) I'm also attaching the two comp photos I used.

How do I get the image of the couple running to be sharp?

Thanks.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4812

Did you scale them down in one shot, or did you perform several scale-down steps?

Wallace · **Posted:** Sat Jul 16, 2016 8:41 pm **(#3)**

I first opened the running couple and cropped the image with a selection,
as closely as I could.
The less data in the image the better.

I measured against your running couple to get an approximate size for my running couple.

I then scaled my couple close to the measurement taken form your couple.
Using Scale Image, with chain connected.

Lastly did a bit of sharpening on the running couple.
Here's my results.

Attachment:

blur 2.xcf [2.15 MiB]
Downloaded 667 times

iggy · **Posted:** Sun Jul 17, 2016 4:30 pm **(#4)**

ofnuts wrote:

Did you scale them down in one shot, or did you perform several scale-down steps?

I just scaled down the runners (in one shot) (they were together). I did no scaling of the photo of the train tracks.

Ah, I see what you're asking now. Yes, I scaled the runners multiple times until I was satisfied with their size (but not with the blurriness). So that multiple scaling led to at least some of the blurriness?

iggy · **Posted:** Sun Jul 17, 2016 5:23 pm **(#5)**

Wallace wrote:

I first opened the running couple and cropped the image with a selection,
as closely as I could.
The less data in the image the better.

I measured against your running couple to get an approximate size for my running couple.

I then scaled my couple close to the measurement taken form your couple.
Using Scale Image, with chain connected.

Lastly did a bit of sharpening on the running couple.
Here's my results.

[ Image ]

[ Image ]

Attachment:

The attachment blur 2.xcf is no longer available

Thanks Wallace. And thanks for the step-by-step explanation. I attempted to recreate your process (with a single scaling) (see attachment) (I put the girl side by side for comparison's sake) and yet my girl is still blurrier than yours (though MUCH better than my original). So the only thing I didn't do was your sharpening. How did you do that?

Wallace · **Posted:** Sun Jul 17, 2016 5:48 pm **(#6)**

iggy wrote:

Thanks Wallace.
And thanks for the step-by-step explanation.
I attempted to recreate your process
(with a single scaling)
(see attachment)
(I put the girl side by side for comparison's sake)
and yet my girl is still blurrier than yours
(though MUCH better than my original).
So the only thing I didn't do was your sharpening.
How did you do that?

If you're asking about sharpening the image/girl.
This is what I did.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4812

iggy wrote:

ofnuts wrote:

Did you scale them down in one shot, or did you perform several scale-down steps?

I just scaled down the runners (in one shot) (they were together). I did no scaling of the photo of the train tracks.

Ah, I see what you're asking now. Yes, I scaled the runners multiple times until I was satisfied with their size (but not with the blurriness). So that multiple scaling led to at least some of the blurriness?

Yes... each scaling adds a little blur because pixels are interpolated(*). This is hardly visible on the first, barely visible on the second, but starting with the third it becomes noticeable.

(*) this happens with other Transform tools as well: rotation, perspective, shear...

iggy · **Posted:** Mon Jul 18, 2016 3:01 pm **(#8)**

Wallace wrote:

iggy wrote:

Thanks Wallace.
And thanks for the step-by-step explanation.
I attempted to recreate your process
(with a single scaling)
(see attachment)
(I put the girl side by side for comparison's sake)
and yet my girl is still blurrier than yours
(though MUCH better than my original).
So the only thing I didn't do was your sharpening.
How did you do that?

If you're asking about sharpening the image/girl.
This is what I did.

[ Image ]

Thanks Wallace. Which do you think is best: the enhance>sharpen, enhance> unsharp mask or sharpen tool in the tool bar?

iggy · **Posted:** Mon Jul 18, 2016 3:03 pm **(#9)**

ofnuts wrote:

iggy wrote:

ofnuts wrote:

Did you scale them down in one shot, or did you perform several scale-down steps?

I just scaled down the runners (in one shot) (they were together). I did no scaling of the photo of the train tracks.

Ah, I see what you're asking now. Yes, I scaled the runners multiple times until I was satisfied with their size (but not with the blurriness). So that multiple scaling led to at least some of the blurriness?

Yes... each scaling adds a little blur because pixels are interpolated(*). This is hardly visible on the first, barely visible on the second, but starting with the third it becomes noticeable.

(*) this happens with other Transform tools as well: rotation, perspective, shear...

Wow. Thanks, ofnuts. I did not know this. So really it would pay to do all your editing on a copy, record the settings you used, and then implement all the editing on the original, no?

Wallace · **Posted:** Mon Jul 18, 2016 3:18 pm **(#10)**

iggy wrote:

Thanks Wallace.
Which do you think is best:
the enhance>sharpen,
enhance> unsharp mask or sharpen tool in the tool bar?

In my opinion,
I feel that the regular Enhance>Sharpen would offer less intrusive sharpening overall.
Given the size of the image.
The other methods might be over-kill or make the images seem over-blown.

iggy · **Posted:** Mon Jul 18, 2016 4:32 pm **(#11)**

Wallace wrote:

iggy wrote:

Thanks Wallace.
Which do you think is best:
the enhance>sharpen,
enhance> unsharp mask or sharpen tool in the tool bar?

In my opinion,
I feel that the regular Enhance>Sharpen would offer less intrusive sharpening overall.
Given the size of the image.
The other methods might be over-kill or make the images seem over-blown.

Thanks Wallace. You also have quantitative control that you don't have in the sharpen tool.

Wallace · **Posted:** Mon Jul 18, 2016 4:52 pm **(#12)**

iggy wrote:

Thanks Wallace. You also have quantitative control that you don't have in the sharpen tool.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4812

iggy wrote:

Wow. Thanks, ofnuts. I did not know this. So really it would pay to do all your editing on a copy, record the settings you used, and then implement all the editing on the original, no?

That would be extreme... The idea is more than if you don't achieve the result on the first try, instead of "fixing" the incorrect result, Ctrl-Z and do it over.

AKMusician · **Joined:** Jun 30, 2016 **Posts:** 16

Unsharp mask is my only sharpening tool. The blur radius, amount, and threshold parameters give you absolute control. For example, a radius of 0.5-2.5 (dependent on the size of the image) and an amount of 0.65-1.0 yields a very pleasing result.

I also use it in almost every photo as a local contrast enhancer. Here's a great article about it:
http://blog.patdavid.net/2014/08/clarit ... tones.html

iggy · **Posted:** Mon Jul 18, 2016 7:39 pm **(#15)**

ofnuts wrote:

iggy wrote:

Wow. Thanks, ofnuts. I did not know this. So really it would pay to do all your editing on a copy, record the settings you used, and then implement all the editing on the original, no?

That would be extreme... The idea is more than if you don't achieve the result on the first try, instead of "fixing" the incorrect result, Ctrl-Z and do it over.

Thanks ofnuts. Just to make sure I understand.

1) is the edit>undo the same as ctrl Z ?
2) So practically speaking. I scale the image. I don't like the results. Rather than scaling the image again I do ctrl Z and try again. Or if I'm using the the rotate tool for instance, same sort of thing. If I don't like the results, rather than rotating again right away, I hit ctrl Z and then try again. Would this be correct?

iggy · **Posted:** Mon Jul 18, 2016 7:47 pm **(#16)**

AKMusician wrote:

Unsharp mask is my only sharpening tool. The blur radius, amount, and threshold parameters give you absolute control. For example, a radius of 0.5-2.5 (dependent on the size of the image) and an amount of 0.65-1.0 yields a very pleasing result.

I also use it in almost every photo as a local contrast enhancer. Here's a great article about it:
http://blog.patdavid.net/2014/08/clarit ... tones.html

Thanks AK. And thanks for the number guidelines. I tried it and things looked very nice. And thanks for the link. That's quite an article. I'll explore it in detail when I get a chance.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4812

iggy wrote:

Thanks ofnuts. Just to make sure I understand.

1) is the edit>undo the same as ctrl Z ?
2) So practically speaking. I scale the image. I don't like the results. Rather than scaling the image again I do ctrl Z and try again. Or if I'm using the the rotate tool for instance, same sort of thing. If I don't like the results, rather than rotating again right away, I hit ctrl Z and then try again. Would this be correct?

Yes to both.

iggy · **Posted:** Tue Jul 19, 2016 1:37 pm **(#18)**

ofnuts wrote:

iggy wrote:

Thanks ofnuts. Just to make sure I understand.

1) is the edit>undo the same as ctrl Z ?
2) So practically speaking. I scale the image. I don't like the results. Rather than scaling the image again I do ctrl Z and try again. Or if I'm using the the rotate tool for instance, same sort of thing. If I don't like the results, rather than rotating again right away, I hit ctrl Z and then try again. Would this be correct?

Yes to both.

Thank you.