Larger image and take off noise, pixel dust, blur

aquarius · 09-25-2003, 09:57 AM

Heya, friends!

I'm newbie in graphics, so the problem is: I've got an image (495*500) of not perfect quality. I need to make it ~ twice bigger and take off this shit, that appears, when the image is larger - pixel dirt, dust, noise, blur, bad color and other crap.....

Please, if someone knows - help me!

Thanx in advance.

BRUSTR · 09-25-2003, 01:18 PM

I am afraid their is no quick fix for this.
To get rid of the noise, dust etc your best friend is probably going to be the clone tool. Select an unblemished area of similar color to the bit with the noise, and clone it over the top. Do this before trying to sharpen the image otherwise you are going to amplify the noise in the image.

For sharpening you are probably best using the unsharp mask as it is more adjustable than other sharpen filters.
Their is a technique which will allow you to sharpen JUST the edges, I can't remember the specifics off the top of my head but it involves running the find edges filter on a copy of the best contrast color channel in your image, and then using that as mask for the sharpen operation, a quick google should find something similar.

For color adjustment if it is selected areas that are the wrong color then you are probably best creating a mask of those areas and using an adjustment layer. If it is the whole image then try the variations option, or for tighter contorl use an adjustment layer.

If you post a copy of the image we can look at it and make better suggestions. If you need more info on anything then shout and holla and someone will be able to help out.

[edit] Just found a tutorial for the sharpening http://www.creativepro.com/story/feature/12333.html

Where it says duplicating a channel in your image works well, look at the channels and pick the one with the best contrast and/or the least noise.

CC

Lompoc42 · 09-25-2003, 02:27 PM

That's a great resource there CC and that method certainly looks like something to pay attention to Aquarius. Just remember however, that you're dealing with the double of image sizing. You can have an original image and go smaller without any loss in resolution. However when you try and make it bigger you will end up with a pixelated mess. This is because you're trying to expand already existing pixels into a larger area. Hence you will get poor quality. When you shrink an image down you're cramming more pixels into a smaller space. This is why some people when doing photo manipulations will shrink their images down, because it will actually mask out some problems.

Here's a trick I used to use when I was working with jewelry for ads. If you have a really bad source image on the computer then print it out on as high a quality printer and paper as you can. Then scan the image at a super high resolution. Granted you have to do some scan touch ups because of this, but if you really need it big and beautiful and you have no other options, then I think this is probably your best bet!

Hope this helps.

KOP

Blinky2004 · 09-25-2003, 08:48 PM

Ya nice idea Lompoc. And use photo paper too. Matte if you can find it.

Just to make this perfectly clear in the mid, think of sizing up a photo like stretching a wool knit sweater... when you stretch the sweater, holes appear between the strands of wool, right? Well the same thing happens to your image in PS when scaling up. And Photoshop is left to try a guess what to fill those holes with, so far as colour is concerned.
Generally, PS will use neighbouring colours to draw this data from, but it's still a guessing game. Hance the results will always be crap.

Photoshop does a much better job of guessing what to toss out when scaling down, than it does faking it when scaling up.

KOP

I like that!