Question

Can I control DPI when I convert a pdf to a tiff?

  • 29 November 2018
  • 3 replies
  • 12 views
J
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Hello,

I have a simple workspace that renames and exports pdf documents to tiffs. Its the PDF2D reader, some renaming transformer,s and the TIFF writer. The tiffs need to be 400 dpi. No matter what I do, I only get 96 dpi. Is there a way to control this?

I have been able to get the 400 dpi using other software, but it's either clunky or will cost me more money. FME is obviously the preferred method if I can fulfill this one requirement.

I appreciate any help.

Thank You,

 

FME(R) 2018.1.0.1 (20180730 - Build 18528 - WIN64)

3 replies

G
Badge +3

@justinv

you can just calculate the amount of pixels required and use it as input for number of columns/rows

400*image_width (inches of course) and then use a RasterResampler.

Then send it to the writer.

 

On the other hand the writer has:

 

geotiff_tifftag_

 

resolutionunit

The unit of measurement for 

geotiff_tifftag_xresolution
 and 
geotiff_tifftag_yresolution
. The possible values are 1, which means that there is no absolute unit of measurement and is usually used for images, 2, which means inches, and 3, which means centimeters.

geotiff_tifftag_

 

xresolution

Represents the number of pixels per 

geotiff_tifftag_resolutionunit
 in the x direction.

geotiff_tifftag_

 

yresolution

Represents the number of pixels per 

geotiff_tifftag_resolutionunit
 in the y direction.

 

 

 

 

 you probably could use these to control dpi (same technique as previously described)

https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_ReadersWriters/geotiff/Feature_Representation.htm

 

Of course a low dpi input will not improve by upping the dpi.

redgeographics
Rank
Userlevel 5
Badge +25

@justinv

you can just calculate the amount of pixels required and use it as input for number of columns/rows

400*image_width (inches of course) and then use a RasterResampler.

Then send it to the writer.

 

On the other hand the writer has:

 

geotiff_tifftag_

 

resolutionunit

The unit of measurement for 

geotiff_tifftag_xresolution
 and 
geotiff_tifftag_yresolution
. The possible values are 1, which means that there is no absolute unit of measurement and is usually used for images, 2, which means inches, and 3, which means centimeters.

geotiff_tifftag_

 

xresolution

Represents the number of pixels per 

geotiff_tifftag_resolutionunit
 in the x direction.

geotiff_tifftag_

 

yresolution

Represents the number of pixels per 

geotiff_tifftag_resolutionunit
 in the y direction.

 

 

 

 

 you probably could use these to control dpi (same technique as previously described)

https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_ReadersWriters/geotiff/Feature_Representation.htm

 

Of course a low dpi input will not improve by upping the dpi.

To add to what @gio wrote: the dpi value in a TIFF is purely to tell software how big the image will be in print (although graphics software can override it). It has no influence whatsoever on the number of pixels.

J
Badge

@justinv

you can just calculate the amount of pixels required and use it as input for number of columns/rows

400*image_width (inches of course) and then use a RasterResampler.

Then send it to the writer.

 

On the other hand the writer has:

 

geotiff_tifftag_

 

resolutionunit

The unit of measurement for 

geotiff_tifftag_xresolution
 and 
geotiff_tifftag_yresolution
. The possible values are 1, which means that there is no absolute unit of measurement and is usually used for images, 2, which means inches, and 3, which means centimeters.

geotiff_tifftag_

 

xresolution

Represents the number of pixels per 

geotiff_tifftag_resolutionunit
 in the x direction.

geotiff_tifftag_

 

yresolution

Represents the number of pixels per 

geotiff_tifftag_resolutionunit
 in the y direction.

 

 

 

 

 you probably could use these to control dpi (same technique as previously described)

https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_ReadersWriters/geotiff/Feature_Representation.htm

 

Of course a low dpi input will not improve by upping the dpi.

@gio @redgeographics

Thank you for the help. That does the trick. I understand that changing the DPI does not change the quality of the image or the print. This was just a requirement to get images through some legacy software that is a bit inflexible.

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