Quick question about Photoshop

[illgiveumorality]

Had a thought today:
Is it standard practice to upscale photos (i.e. double the resolution) when you are working on an image?

 

[madFive]

Nope - upscaling, as a general rule of thumb, is a very bad idea. If, like you said, you exactly doubled (or larger multiple) the height/width of the image, at least (theoretically) each pixel would be preserved, and you wouldn't degrade the image quality - but really you still didn't improve anything; but if you try to upscale an image to a non-multiple size, all kinds of nasty stuff tends to happen - you'll get distortion and blurred pixels across the entire image. I'm sure the algorithms have improved since the beginnings of Photoshop, and it may look a little better now than it used to, but in general, it's still considered a big no-no!

If you absolutely have to do upscaling, there are plug-ins you can get that will minimize the damage and try to give you a clean sharp image as result, but generally the garbage-in-garbage-out rule holds true. So up-scaling an image almost always makes it look worse. Try, if at all possible, to obtain the high-res source image and work down from that, not vise-versa.

 

[illgiveumorality]

What about when working with heavy effects? For example, using an image as a baseline for its contours/fundamental color scheme, but allowing the processing to render at a higher resolution?

I guess the answer to my question is probably- those who are doing anything serious will refuse to start with a lower resolution than their output resolution.

 

[jiminator]

if your intent is to upscale, add effects and then downscale back to the original resolution then that should work. depending on the processing you are doing you might see better results. might also see artifacts though.

 

[DeathPrincess]

just dont use sharpen...sharpen on large images in photoshop doesn't work so well. Might be the same for other effects too. When the pixels become 4 pixel blocks it interprets items differently, so noise reduction etc has to be more aggresive.

 

[madFive]

What about when working with heavy effects? For example, using an image as a baseline for its contours/fundamental color scheme, but allowing the processing to render at a higher resolution?

I guess the answer to my question is probably- those who are doing anything serious will refuse to start with a lower resolution than their output resolution.

Not quite sure I'm following you - what kind of effects? I'm not aware of any PhotoShop filters that work better on a stretched image, but I guess it is possible. You're probably better off either leaving the image at the original resolution, or doing your effects in a vector-based program, so the difference in resolutions won't matter so much.

If we're talking about bringing in a low-res bitmap, then painting on top of it for a completely different final image, then yeah, you'll want to set up your file at the output resolution, then import the source image and stretch it up to fit, do you painting etc, then you'll probably want to discard the source layer and leave it out of the final product if at all possible.

There are also plenty of instances where you would bring in a relatively low-res (200-300dpi) bitmap into a vector program like illustrator and use it as a texture along with your vector graphics – same with most print-layout programs like InDesign. In that case, you still wouldn't be stretching the original bitmap, you're just mixing dpi levels between the bitmap and vector graphics - and just let the printer sort out the difference.

But really there are always instances where breaking the rules works just fine (maybe you want some grain and distortion in your final image for some reason!), and instances of less than best-case-scenario where you just have to make do with what you have - so if you really need to, go ahead and take the low-res bitmap, upscale, and filter the hell out of it 'till it looks half-way decent at the output res.

 

[ben chi(f4)]

Only time I upscale is when I hit the magnifying glass LOL. But, never upscale as you'll get pixelated images. Shoot in a higher res format if you want larger canvases.