Decal Scanning Questions

[lcorinth]

When scanning decals to reprint later, I've heard the preferred resolution is 300 dpi. But is there a preferred file format to save them in? PDF? TIFF? Something else?

Also, if you have several separate scans, is there a way to print them all on one sheet, to avoid using a whole decal sheet for one item?

What if the opposite is your problem - you already have a scan of a whole sheet from one rocket, but just want to separate out and print one item. Is that possible?

Thanks!

 

[rharshberger]

IMO, PDF is a better format as it is a vector format. As for separating one decal out that is possible and I have done it using Inkscape and the tracing function. Even using the tracing function and ungroup and break apart functions it still takes a lot of time to get a decal sheet to the point of being easy to resize or alter colors, etc. Once the decals have been reworked re-arranging them on a single 8.5x11 sheet so you can print them how you would like to save paper is doable, in some cases doing two sets of decals on the same sheet is possible. As for the separate scans once the sheet has been processed its usually a simple cut and paste to a new document, arrange as preferred, possibly do some size adjustments (the reason I always include a 1" x 1/8" block in my decals. TIFF's are also fairly easy to convert using Inkscape. Easy is a relative term, once learned the process is "easy" but still contains lots of steps.

 

[K'Tesh]

.pdf files preferred, .tif files are good too. I don't care for .jpg files as they get artificial color blobs that occur around any defect in the scanned decals and the edges between colors are often blurry because of this.

And don't forget to include a good* ruler along with the decal. I've seen Home Depot rulers used, and I can't use them as: First, I don't have one here to measure against. Secondly, they're impossible to find in China, And thirdly, they are more what you'd call "guidelines" than actual rules. (nod to Captain Barbossa)

*Drafting type rulers are best: thin, flat metal or (often flexible) plastic with 1mm / 1/16" measurements (or finer)). NOT the hard, inflexible school type rulers that are often made of wood or plastic (you can't get them to lie flat against the edge of the decal sheet).

 

[manixFan]

I teach both Photoshop and Illustrator so I do have some background for this topic.

If you scan an image and save it as a PDF, it isn't converted into a vector format. It's saved internally using JPEG compression, which is not good for line art (solid color artwork like decals). So for decals PDFs are not a good choice if they are scans. (Unless you can override the default JPEG compression when you save the file, which many programs do not offer.) However you scan the images and then convert them into vector artwork in Illustrator. In that instance the PDF format does save the art as vectors which is a much better (and smaller) format for line art.

So, PDF is not a good format for scanned files but a is good format for vector files.

TIFF and PNG are good formats for scans like decals as they offer lossless compression that does not introduce artifacts. PNG files can also be saved as 8-bit (line art mode), further reducing file size without a loss in quality.

JPEG is the worst format for line art as it is a lossy compression format that introduces 'blobs' as K'Tesh calls them. If they are saved at a very low compression ration (or a high quality setting) the effects are generally not noticeable.

Using Photoshop and Illustrator you can take a good scan of a decal sheet and turn it into vector artwork that can be easily resized and is much smaller than the original scan in about 10 minutes. For poor quality decals you can trace over the original image manually in Illustrator and create new artwork from scratch.

Attached is an example of a quick cleanup of a scan. Took less than a minute. I also made a vector PDF from the scan using the image trace function in Illustrator. Whole process took less than 10 minutes. Converted to vector art the PDF is only 136K.

Just FYI,


Tony

before and after:

 

[K'Tesh]

I suspect that part of my problem with .jpgs is that often they are scanned in, saved as .pdf files, then exported and saved again as .jpg which gives the image a chance to pick up the "blobs".

 

[manixFan]

You are correct in that opening a JPG and then re-saving it can lower the quality and add artifacts. I demonstrate this by folding a piece of paper in fourths, un-folding it, then refolding it in thirds. When unfolded the second time it has a lot more creases which I equate to JPG compression artifacts. Neither TIFF (unless you choose JPG when you save it) or PNG create the same kind of artifacts.


Tony