Did you ever notice? - DPChallenge Forums

09/24/2013 07:18:15 PM · #1

I have PS CS6 like many of you, I'm sure. When I select "fit to screen" the image goes slightly soft. When I zoom in or zoom out, (at any other size other than fit to screen), it snaps into sharp focus. A friend of mine say's it's happening with his CS5 as well.

I wondered if any of you folks are noticing this and would you have any idea as to why this might be happening?

Message edited by author 2013-09-24 19:18:50.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/24/2013 10:08:09 PM · #2

This always happens when the display or photo resolution is not an "even" factor or multiple of the original size ... the image will look sharp at 25%, but terrible at 26.4% (a possible "fit to screen" value). If you're not halving or doubling the value you get "fractional" pixels involved in the computations -- it's impossible for the screen to represent 2/3 of one pixel and 1/3 of the neighboring one -- it has to "pick" one or the other or a compromise which is neither.

This is the same rationale I use in sizing my entries to 704 pixels instead of 800 -- it's exactly 25% of the native size of the original image, so every "new" pixel is made up of exactly four pixels in the original, without any "contamination" from any surrounding pixels. It is my (unproven but logical) presumption that this helps preserve detail.

Message edited by author 2013-09-24 22:09:19.

tanguera

Nikon D750

Nikon AF-S Nikkor 17-35mm f/2.8D IF-ED

09/24/2013 10:17:10 PM · #3

The information known by some people just boggles my mind!!!

artistChan

Canon PowerShot SX30

09/24/2013 10:47:50 PM · #4

Originally posted by tanguera:

The information known by some people just boggles my mind!!!

Absolutely

09/26/2013 04:24:28 PM · #5

Originally posted by GeneralE:

GeneralIE knows his stuff. I've learned much from his comments before. This one was brilliant. Who the heck would have known this?

So I created another thread and asked what the best size was for entering images in challenges. This issue was the reason I asked the question. GernalIE gave me (us) this sizing suggestion in that thread but didn't explain the rationale behind it. Now I get it and this should really help me improve my (our) onscreen sharpness.

Thanks GeneralIE keep those comments coming! (smile)

09/26/2013 04:26:32 PM · #6

Originally posted by Trotterjay:

Originally posted by GeneralE:
This always happens when the display or photo resolution is not an "even" factor or multiple of the original size ... the image will look sharp at 25%, but terrible at 26.4% (a possible "fit to screen" value). If you're not halving or doubling the value you get "fractional" pixels involved in the computations -- it's impossible for the screen to represent 2/3 of one pixel and 1/3 of the neighboring one -- it has to "pick" one or the other or a compromise which is neither.

This is the same rationale I use in sizing my entries to 704 pixels instead of 800 -- it's exactly 25% of the native size of the original image, so every "new" pixel is made up of exactly four pixels in the original, without any "contamination" from any surrounding pixels. It is my (unproven but logical) presumption that this helps preserve detail.

GeneralE knows his stuff. I've learned much from his comments before. This one was brilliant. Who the heck would have known this?

So I created another thread, previous to this one, and asked what the best size was for entering images in challenges. This issue was the reason I asked the question. GernalIE gave me (us) this sizing suggestion in that thread but didn't explain the rationale behind it. Now I get it and this should really help me improve my (our) onscreen sharpness.

Thanks GeneralE keep those comments coming! (smile)

Message edited by author 2013-09-26 16:42:54.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/26/2013 04:50:33 PM · #7

Originally posted by Trotterjay:

... I created another thread and asked what the best size was for entering images in challenges. This issue was the reason I asked the question. GernalIE gave me (us) this sizing suggestion in that thread but didn't explain the rationale behind it. Now I get it and this should really help me improve my (our) onscreen sharpness.

Sorry, I thought I did explain it in the other thread, which I came across before I saw this one, leading to the somewhat backwards explanation.

One suggestion would be to put the actual "problem" in the title of any similar future thread you create â�� this one is rather ambiguous, and even I don't have time to explore (or even see) every thread. I think it would attract more helpful attention more quickly if you called it something like "Need helpâ��soft images on monitor."

blindjustice

Canon EOS-7D

Canon EF 17-40mm f/4.0L USM

09/26/2013 04:59:11 PM · #8

1/5 or 20% of my native resolution is 777.6. is that the size I should make it instead of 800?

Cory

Canon EOS-1D Mark IV

Canon EF 85mm f/1.2L II USM

09/26/2013 05:07:26 PM · #9

Originally posted by blindjustice:

1/5 or 20% of my native resolution is 777.6. is that the size I should make it instead of 800?

Just gonna weigh in here and say that I think if you go for 1600 pixels as an intermediary step, there's no reason to not resize to the full 800 pixels. Effectively, you'll then go 4:1, and get fine downsampling.

A theoretical advantage of partial pixel downsamples is the fact that you'll get some level of noise reduction benefit, because of the inherent minor loss of detail that occurs.

Of course, the second resize to 800 from 1600 more than makes up for that, especially if you over-sharpen at the 1600px stage.

I just can't see any advantage to going directly from initial resolution to final resolution, as opposed to having an intermediary stage with a 4:1 ratio.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/26/2013 05:13:19 PM · #10

Originally posted by blindjustice:

1/5 or 20% of my native resolution is 777.6. is that the size I should make it instead of 800?

You're now talking about sizing for challenge entries, not just monitor display issues, right?

If your original is really 3888 pixels ... I think I'd first crop off three pixels to make it 3885, then the 20% scale will make it exactly 777 pixels. If you set it to just scale to 20% the program will probably do some rounding, which may give you the same thing or not -- you might experiment with a detailed image doing it both ways.

It's entirely possible that with this degree of reduction it doesn't make any difference at all which method is used, but yes, I'd scale it to exactly 20% and make it a little smaller, rather than getting to 800 pixels by scaling to 20.576131687242798353909465020576% ... remember that the smaller image will also save you a few KB in meeting the file-size limit as well, and make let you save at a higher-quality JPEG setting, which will also help preserve detail.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/26/2013 05:15:22 PM · #11

Originally posted by Cory:

I just can't see any advantage to going directly from initial resolution to final resolution, as opposed to having an intermediary stage with a 4:1 ratio.

My direct reduction is already 4:1 â�� I'm starting with much smaller files* than you all have become used to ...

*2816 x 2112 JPEG

Cory

Canon EOS-1D Mark IV

Canon EF 85mm f/1.2L II USM

09/26/2013 05:16:58 PM · #12

Originally posted by GeneralE:

Originally posted by Cory:
I just can't see any advantage to going directly from initial resolution to final resolution, as opposed to having an intermediary stage with a 4:1 ratio.

My direct reduction is already 4:1 â�� I'm starting with much smaller files* than you all have become used to ...

*2816 x 2112 JPEG

We're talking about different things. You're talking linear, I'm talking ratios.

That's a 4x reduction, leading to a 16:1 ratio.

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

09/26/2013 05:30:25 PM · #13

If you make your first resize to 3200 pixels, any loss of detail from pixel interpolation is negligible. From that point. go to 1600 and 800 in two steps and you're golden...