Legacy ImageMagick Discussions Archive

Hi,

We have recently moved from outsourcing our dev to doing it in-house. We use imagemajick for any image manipulation. At the moment anyone uploading an image to our site have the option to up-res to press quality (with quality warning). However a lot of people are using QR codes and uploading very low res 1-bit images. Our system currently changes to greyscale and then up-res to 300ppi at the size selected. The results are reasonable, but 1-bit QR codes seem to print better when not turned to greyscale and up-resed (ie left as a 1-bit and just increased in size in Indesign or Quark etc and printed).

So is there a way we could get ImageMagick to recognise that a particular PNG or Tif is a 1-bit file and it won't up-res it as if it was a regular PNG or tif file?

I'm not a programmer, but will forward any questions or comments to our CTO.

Thanks in advance, Tim.

Look at the verbose information (identify -verbose your image). See if it says Type Bilevel and/or Depth 1-bit and/or Channel Depth -> gray 1-bit

Image: rose_1bit.png
Format: PNG (Portable Network Graphics)
Class: PseudoClass
Geometry: 70x46+0+0
Resolution: 72x72
Print size: 0.972222x0.638889
Units: Undefined
Type: Bilevel
Base type: Bilevel
Endianess: Undefined
Colorspace: Gray
Depth: 8/1-bit
Channel depth:
gray: 1-bit




Image: rose_1bit.tif
Format: TIFF (Tagged Image File Format)
Class: DirectClass
Geometry: 70x46+0+0
Resolution: 72x72
Print size: 0.972222x0.638889
Units: Undefined
Type: Bilevel
Base type: Bilevel
Endianess: MSB
Colorspace: Gray
Depth: 1-bit
Channel depth:
gray: 1-bit


perhaps use -sample (rather than -resize) to enlarge to keep it binary
http://www.imagemagick.org/script/comma ... php#sample