SOT: Upscale an image without resampling.

farss wrote on 7/14/2013, 12:08 AM
From time to time I'd like to upscale an image so I can see the pixels in the original.
I realise there's restrictions doing this, the scaling factor has to be a factor of two.
Try as I might I cannot find a way to do this in PS or Irfanview, anyone have any ideas or suggest software that can do this?

Why?
So I can see / show others the differences between lets say 4:2:0 and 4:2:2 sampling.

Bob.

Comments

PeterDuke wrote on 7/14/2013, 2:20 AM
In Photoshop, Ctrl + (or Ctrl =) magnifies the view so that you see the pixels very clearly. Is that what you want?

This happens with photos from my old 5 Mpixels camera, where the sensor resolution is poor compared to the lens. With newer cameras having "high" resolution of say 20 Mpixels, the lens quality may be the limiting factor, so that the individual pixels may not be so clear.
farss wrote on 7/14/2013, 4:10 AM
[I]"In Photoshop, Ctrl + (or Ctrl =) magnifies the view so that you see the pixels very clearly."[/I]

I believe that resamples / interpolates.

Bob.
TheHappyFriar wrote on 7/14/2013, 5:58 AM
I wouldn't think zooming in would resample. That's what the CTRL+ should do.

Gimp has an option for interpolation when you scale the image, I'd ASSUME Photoshop would give you the same option. I remember the older ones did. So I'm sure it's in the Scale options somewhere.
Malcolm D wrote on 7/14/2013, 6:32 AM
Try VuePrint
Every time you click on the image it doubles in size or you can select an area.
To save use Print Scrn.

Malcolm
farss wrote on 7/14/2013, 7:41 AM
Thanks,
VuePrint did come up in my searches as did ways that Photoshop [I]might[/I] do what I want. I just found that SnagIt's editor will sort of do what I want in preview but I cannot save the image that way and darn it, SnagIt will not capture itself.

Anyways I'll give VuePrint a try, heck I might even ask Hamish...

I also realised I was wrong in my initial post, pixels would have to be scaled by a f odd numbered factors e.g. one pixel expands one pixel in each direction to become 3x3.

Bob.
PeterDuke wrote on 7/14/2013, 9:45 AM
"In Photoshop, Ctrl + (or Ctrl =) magnifies the view so that you see the pixels very clearly."

I believe that resamples / interpolates.

Not on my machine. Diagonal lines become a staircase.

musicvid10 wrote on 7/14/2013, 11:04 AM
Irfanview will do what you want and save without Prt Sc. Choose "Resize" instead of "Resample."
The original text, of course, was anti-aliased.



MarkWWW wrote on 7/14/2013, 11:11 AM
Paint Shop Pro will allow you to do this.

In PSP8 (the latest version I have) you can resize with a choice of four algorithms - bilinear, bicubic, weighted-average, and "pixel resize".

"Pixel resize" is the one you want - it "Duplicates or removes pixels as necessary to achieve the selected width and height of the image" (from the Help file). Makes a very blocky image, of course, so one wouldn't use it for most normal purposes, but does exactly what you are wanting in this case.

I must say I'm surprised PS and IrfanView can't do it though.

Mark
musicvid10 wrote on 7/14/2013, 11:37 AM
I don't think Bob wants to "duplicate or remove pixels." That doesn't sound like a pixel-for-pixel transform, as I believe Bob is looking for. Irfanview does that, as illustrated above.

Also, since 4 is the smallest perfect square >1, multiples of two for both dimensions will work fine.