simmy

I've always wondered how sign companies etc can take little digital pictures and blow them up to make big posters, for example I sent a company a picture about 400x400 (pixels) and they enlarged it to wheel cover size without any drop in quality.

Now obviously any paint program can enlarge pictures but the picture becomes blocky as they just inflate the pixels. Is there any software available that can seriously enlarge pictures without losing quality, ie manipulate the pixels, or is it all done by specialised machines???

SS

MarkO

It's not possible to enlarge digital photos without losing quality. The trick is to use a high-res scanner. You can buy a 4000dpi negative scanner from Nikon for £1,200-odd, which will blow up to a decent size (assuming the shot was taken with a slow film - 100iso, for example, and the grain level of the shot isn't too high).

Most professional posters are taken from large-format film, though, and scanned using drum-scanners (which give 12,000dpi or higher). This means that the film source has far more detail, and the scanner can capture more of it.

Having said that, the image sizes are larger, too - for example, my 2,900dpi Nikon neg scanner produces a 32Mb TIFF file from a 24-bit scan at that resolution.

IWatkins

A lot of big signs etc. that are text/graphic only (i.e. no photogs) are created from vector graphics rather than bitmaps. I.e. you make them as big (or small) as you like with zero loss of quality (well. depending on the printer).

MarkO

Good point. If this 400x400 picture you mention was a logo or some non-photographic artwork, the company probably scanned it, and then converted it to vectors by tracing, etc. CorelDraw can do this, for example.

Then the image would be scalable without any loss in the quality or smoothness of the details.

What was the picture - can you post it so we can see?

Ian Griffiths

If it's already in the digital domain at 400 pixels square then the only way you're going to increase the size and not pixelate is by tracing the image to a vector. Even the most expensive scanner is useless with an image that's already a bitmap.

The same technique is also employed to remove grain in areas of colour.

simmy

It is grapics I am speaking about so this vector stuff sounds interesting, I have seen reference to it in Paint Shop Pro.

IT's time to learn something new say I wanted to take the graphic below and enlarge it, what would I have to do??.



From what I've read above, I'm guessing that I would have to create a new layer in PSP and re-draw (by tracing over) the individual shapes and lines as vectors, then I could group all of the shapes into one vector, sound like a labourious process

Is there an easier and quicker way to do it either using PSP or another drawing program??

SS

IWatkins

simmy,

I'm not sure to be honest, as I don't think I've ever done it. But I do understand the theory

I would guess that some of the high end packages could probably have an "Auto Vector" function where it attempts to trace it for you and you then get to adjust the vectors afterwards, but I wouldn't bet on it.

PSP7 does have vector creation tools, but again, don't think I've ever played with them. But I guess you would load you bitmap, create a vector layer, trace over the bitmap, then merge the vector layer to give you a resizable layer.

Cheers

Ian

MarkO

Simmy, get a copy of CorelDraw. It has a trace function which will do a good job of converting a bitmap to a vector. It works particularly well with pictures which use areas of one colour (i.e., no gradients, etc).

JackClark

Poster Printery works great, I made a life size Kylie for my bathroom using it. Registered version was about a tenner. STFI.

Ian Griffiths

Macromedia Flash also has such a function.