Question about large images??

[Francisco perez]

hi everyone!! i'm fairly new to this and love all the great tip's and all the great support!! i have a question about images...... how do you guys do it to engrave a large image with out it distorting or pixelating when enlarging it?? i seen pictures of some awesome work done on tiles, tiles put together to create a large image and the art work looks amazing, i seen a guy here posting his work on tiles and its awesome work, all your tip's and info. are greatly apresiated, thanks!!!

[Darren Null]

Often, the really large images are vector format. Unlike bitmaps, which are a grid of coloured squares that make up an image; vectors are coordinates for lines, circles and vari-shaped blobs,

With bitmaps, once you go over the size the image was intended for, it starts to look pixilated: ie, you can see the individual squares that make up the image.

With vectors, as you scale the image up, all that happens is that the coordinates get spread further apart. A 1" circle becomes a 5" circle; and the same with the lines and blobby bits. So it scales up to whatever size you want with no loss in quality.

Or you can use really large bitmaps. You can scale them up with software to a certain extent (Smilla Enlarger); or you can (for example) take a bunch of photos and stitch them together on the computer. For a really huge installation, though, vectors is the way to go.

EDIT: For lasering only, as it's pure black and white, the free Inkscape program has a pretty good raster to vector tracing routine. Problem with that, is it often needs a lot of simplifying work before Corel can import it without exploding. Both Corel's and Illustrators tracing routines are only so-so IMO.

[Dan Hintz]

To add to Darren's...

Vector images scale perfectly to almost any large size, but some of the large raster images are also taken at a high resolution to begin with. If you're forced to start with a (relatively) low resolution raster image, you'll need a good quality resizing program... the fractal and wavelet-based programs are going to be your best bet (in general... nothing can help a poor implementation). I did my master's research in wavelets, so I'm partial to them as a general class, but fractals can be seen as a subset of them.

That said, there's only so much you can do with an image as you increase the size. The program must make certain assumptions or generalizations about an image that usually does not translate to different types... what works well for images of nature (lots of sharp edges on trees full of leaves, etc.) often do not translate well to portraits (close-up facial images that include large areas of smooth skin), etc. You must either choose parameters that fit the subject matter or live with the compromises the program forces on you.

[Sheryl Haley]

Francisco,
I use a program called Photozoom 3 by Benvista. It will enlarge an image without distorting or pixelating it. I use it all the time. It does such a great job that it was worth the investment.
Sheryl Haley

[Darren Null]

Not used photozoom. The 'industry standard' is -or used to be- 'Genuine Fractals'. I've got comparable (and often better) results from Smilla Enlarger. Free, too.
http://sourceforge.net/projects/imageenlarger/

[Dan Hintz]

Not used photozoom. The 'industry standard' is -or used to be- 'Genuine Fractals'. I've got comparable (and often better) results from Smilla Enlarger. Free, too.
http://sourceforge.net/projects/imageenlarger/
Glad to see someone using it after my suggestion... even I haven't taken the time to play with it yet. :( I think I came across it while searching on some wavelet algorithms, so that is probably what he is using.

[Darren Null]

Definitely worth having- thanks for pointing it out. I've also -by dint of really ramming the size up and then resampling back down to the original (ish) size- I've managed to rescue some images I'd previously thought unsaveable.

I use it:
Presharpen off (photoshop's unsharp mask is better, if needed)
Dithering off (just adds noise- can't see the point unless you're trying to get an '80's porn' look)
DeNoise up high-ish

Excellent program.

[Francisco perez]

Thanks everyone for the help!! I will use the tips you guys gave me and see how it turns out, thanks!

[Jack Harper]

I think this question is related. Does anyone know how to get a .bmp file to go over 30,000 x 30,000 pixels? I have to stay in the bmp world for file/laser compatibility and keep hitting this size wall.

[Darren Null]

Choose your format. TIFF'll go big. Also, corel likes them and imports them as you intended them to be (Corel adds grey pixels to BMP sometimes, which is well irritating). Here's a chart.
http://verylargeimages.blogspot.com/2007/01/existing-tiff-format-is-limited-in-size.html

JPG implodes at 30,000px. In photoshop, and many other other image viewers. Theoretical limit is 64kx64k

PSD- 300kx300k limit

[Dan Hintz]

BMP supports up to 32kx32k images, so you're basically running up against the wall for the format.

TIFF supports up to 4GB files (though many implementations only support 2GB). I'll often use PNG for smaller files, but if you're looking at true-color images (24-bit), stay away, it's a pig for large images.

You do not want JPG for smaller images that are increased in size. Even at the highest quality settings, the nature of the DCTs used in JPG compression push the errors towards the edge of the block, making them highly visible, not to mention you lose any space savings by going with a high quality.

[Jack Harper]

Unfortunately, Vytek lasers can only use .bmp files. The file must be saved in that format and then you have to hand load the file into the machine using its control pad. They are happy to brag about the machine size and max resolution, they just don't tell you no such software can actually create a file to take advantage of their max hardware abilities.

[Darren Null]

You can always work with your image in photoshop (psd or tiff) and dice it into BMP chunks for your laser.

The way I do it is:

Rectangular Marquee Tool

Fixed Size (Drop bar at top- usually says 'Normal', but you can also choose 'Fixed Ratio' and 'Fixed Size'). Set to desired number of pixels- say 20 000 width and height.

Copy and paste into a new layer.

Line up the next chunk. I do this by switching off the main image on the bottom layer and zooming right in to plink in the selection box in the right place.

Now you're lined up, remember to switch to the bottom layer and turn it on. Copy and paste the next chunk.

Lather. Rinse. Repeat.

SO, now you have the image diced up into chunks of a suitable size, all on different layers.

Click the layer your first chunk is on.
Select --> Load Selection --> [OK]
Copy --> File --> New File --> [OK] (or CTRL-C --> CTRL-N --> [OK])

Lather. Rinse. Repeat.

So now you have your image diced up into chunks, each in a separate image. SAVE AS --> BMP. Done. Remember to give yourself a logical naming system:
1a, 2a, 3a
1b, 2b, 3b
...etc

And you're good. I don't know how you'd feed them into your particular machine, nor how you'd position the head to burn each chunk in the right place.

I do know that in Coreldraw the chunks snap together nicely and you can burn a large image by deleting all but 1 of the chunks; print; undo delete; and on to the next one. (My print buffer is crap, as well, which is how I know).

All of the above sounds complicated, but is much much easier than it sounds. Just a little repetitive.

[onur cakir]

I follow a not so-technical way for images :)

I buy artbooks and scan pages in 600 DPI. Althought i have a scanner at office, i scan them in a pro-copy shop. Their 72 DPI is like our home scanner's 300 DPI.

With pro scanned 600 DPI i get around 30 mb file size for A4.

Than its easy to enlarge it with ps without loss in quality.

[Jack Harper]

You can always work with your image in photoshop (psd or tiff) and dice it into BMP chunks for your laser.

The way I do it is: ...

Darren - Thanks for the suggestions. Unfortunately, my problem is I need a single file as large as 1000dpi covering 72" x 120" and has to be .bmp that can be run at one time.

[Darren Null]

well 1000dpi'll get you to 32x32". But why 1000dpi? 300dpi 'll get you nearly there (106") and 254dpi (the limits of 20/20 vision, I read somewhere the other day) will fill your area up. 266.6 recurring, so say your bitmap is 260dpi, you'll have 3 inches-worth of pixels to spare on the large side. And should still look OK. Pity you can't nick some pixels from the short side, but such is life.

[Jack Harper]

I do this large engraving where i need to remove some very tough paint and it can take a lot of passes to get it off without over-driving the glass.

[Darren Null]

BMP won't do it. Your machine only does BMP. Upgrade/update the machine or use paint that isn't so tough are the only solutions that come to mind.

How about seeing if Vytec have a solution. Standard print res is 300dpi, which won't do the table of the machine. They must have encountered the problem before and may have a workaround. Worth an ask.

[Steve Clarkson]

OK.....I just used BenVista PhotoZoom Pro 2 for the first time.....I took a 5"x5" bitmap and blew it up to 60"x60"....it looks BEAUTIFUL!!!! Took about 30 seconds.

[Gary Hair]

OK.....I just used BenVista PhotoZoom Pro 2 for the first time.....I took a 5"x5" bitmap and blew it up to 60"x60"....it looks BEAUTIFUL!!!! Took about 30 seconds.



I've been using PhotoZoom Pro for about 3 years and I'm completely impressed! I have never had an image that didn't turn out fantastic and much better than any other program I tried to use. I don't remember the technicalities now, but the algorythm they use is different than most programs use and is more "intelligent" in deciding what pixels to do what with. I forget what it cost me, but whatever it was, was well worth it! I had done some murals with 4x6 photos that would blow your mind.

Gary

[Darren Null]

They're up to version 3.

[Dan Hintz]

Darren, there's a reason Steve is using version 2 which will be revealed in a few days...

[Darren Null]

Is this one of those "how do you keep an idiot in suspense" jokes?

[Dan Hintz]

Is this one of those "how do you keep an idiot in suspense" jokes?
I'm not sure, how "in suspense" are you? ;)

Give it a few days... one of us will explain then, and then you'll smack your forehead.