Posters

[Sardoo]

I would like to create posters for decorating 28mm street scenes. Wondered if anyone could suggest the best application for reducing a picture in size without losing quality?

[mikedemana]

I use Photoshop. Not cheap, but it can also be used on your photos (obviously), making banners, etc.

Mike Demana

[Cherno]

GIMP is a free PS alternative.

[Mitch K]

Beggaring about with jpeg artwork seems fraught with problems as far as quality loss is concerned. I've had more luck using Inkscape to convert the art to vectors, and playing about with them in this form.

There are people on here who really know how to do this stuff (but I can't remember who! ) and hope fully they willchip in on this

[Mr.J]

You can legally download Photoshop 2 for free now. I still have no idea how to use it, but at least it was free!

[FramFramson]

Well, reducing an image size will always involve loss of information, because the image is smaller. HOWEVER, if you have a big, good-quality image which you are trying to make into a small, quality image you'll be fine. The only real problem there is if the image is shrunk a lot and has tiny details or fine text, you might not be able to see/read those. So you should pick images will will read well at a smaller size - which poster-makers would have to do in the real world, because posters are often intended to be seen from far away! But that's a design issue, not a re-sizing issue.

What's genuinely problematic is when you have to take a small image and blow it up, for example resizing a block of, say, 4 pixels to a block of 64. The information just doesn't exist to fill those gaps and bad TV shows where policemen or whiz kids tell a computer to "Enhance" a blurry low-grade image are just so much baloney. You can't create the missing pixels out of imaginary nothing.

[Cherno]

You can legally download Photoshop 2 for free now. I still have no idea how to use it, but at least it was free!

No, PS2 isn't available for (legal) free download. Adobe only made it available for download to it's existing customers because there was a problem with a number of sold activation codes. If you don't have one, you can't download it.

[Dolmot]

To answer the original question, it doesn't really matter.

Some math: Let's assume you want to represent an A2 poster (420 x 594 mm, 16.5 x 23.4"), which is already quite big.

Then we'll pick a scale factor for 28mm. (Oh dear.) Let's say 1/56 is good enough. The miniature poster will be 7.5 x 10.6 mm, 0.29 x 0.42". That right, a largish poster will be 1 cm or 0.4" high, roughly a third of male height as it should be.

A lot of professional printing is done at 300 dpi (dots per inch). 600 dpi is already high quality and you may not really get anything that good out of a basic printer and paper.

Thus, our poster will be:
89 x 125 pixels at 300 dpi
177 x 251 pixels at 600 dpi

The latter is pretty much the maximum you can actually print and distinguish. Meanwhile, it'll probably be a great deal sharper than any painting we can do at 28mm. Try scaling a photo of a 30mm high mini to 600 dpi. It will be about 700 pixels high, head to toe, and quite ruthless in the amount of detail you can see.

So, any source material which is 250 pixels high would be "perfect quality" for this task, and even 125 is still quite adequate. Most of the time you'll be downsampling heavily. There are many different algorithms like nearest neighbour, bilinear, bicubic etc., but even the cheapest software will have plenty of those options available, and the difference is negligible in a task like this. Basically the algorithm choice will affect just single pixels, which won't be really visible in the final print. You should be worrying more about your printer quality and settings, calibration, paper choice, protective coating and so on.

Besides, you can always just drop the full resolution image to image or text processing software, define the print resolution/dimensions, and let the program or your printer driver sort it out. Most likely it will do just fine.

I can illustrate this further with examples if you're really interested.

[has.been]

I have had reasonable results by filling an A4 sheet with bits cut out of colour magazines. Things such as food lables, DVD adverts etc. then reducing the photo copy size. This process can be repeated i.e.put the reduced page on the photocopier & reduce again. Yes the detail is not brilliant, but as they end up as distrssed posters I don't care. The big advantage for me is that it is very low tech.

[Ragnar]

I had great success simply saving images, inserting them to a word document and sizing to the desired dimensions.  I then printed out using a laser printer and highest print setting.

[Sardoo]

Great stuff, folks! Thanks!

[Mr.J]

No, PS2 isn't available for (legal) free download. Adobe only made it available for download to it's existing customers because there was a problem with a number of sold activation codes. If you don't have one, you can't download it.

I got it legally and legitimately about a month ago for free, by reading around it seems they have back peddled and you can't get hold of it any more.