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Modifying dpi

WillanikWillanik Posts: 44
in New Users

Hope someone can help me as I am still a bit of a noob at this.  I am using Daz 4.9, and Iray for my renders.  According to my picture viewing program, my renders are all made at 120 dpi and I my current understanding is that I cannot change this within Daz. 

Here is an example of my problem.  If I render at a width of 1200 pixels, at 120 dpi my unmodified picture width is ten inches.  If I then want a picture of five inch width I can resize to 600 pixels ( or render at 600 pixels in the first place), but my preference would be to increase the dpi to 240 and achieve a five inch picture with 1200 pixels and better definition than the one achieved by simply reducing pixels.

I currently use a free program called Irfanview to view my finished work; it offers me the ability to resize but not to change dpi.  I have read of others increasing the dpi via software such as Photoshop but I am seeking to avoid the expense of such a program.  Are there any other programs out there that can help me change dpi?   Or even better, is there a way to set render dpi in Daz 4.9 that I am not aware of?  

Grateful for any advice!

Comments

  • LyonessLyoness Posts: 1,632

    I use faststone Image viewer. I like it better than irfanview and you can change the dpi.  I regularly use it after I make my thumbnails to size them them 72 dpi for viewing in Daz Studio.
    I've asked the Daz Studio makers and there is no way to change the dpi settings inside of DazStudio so, we are both stuck using an outside program to do it.

  • SpottedKittySpottedKitty Posts: 7,232
    Willanik said:
    I currently use a free program called Irfanview to view my finished work; it offers me the ability to resize but not to change dpi.

    Yes it does; open the Image Properties dialog, enter the DPI you want in the boxes, click the "Change" button, then save the image. Remember the usual warnings about loss of quality/sharpness if you've saved the render as a jpg file.

    Note that D|S does not set a DPI value. What you're seeing is the default value your viewing program uses if an image doesn't have DPI set.

  • FishtalesFishtales Posts: 6,212

    The 72 DPI and the 120 DPI are actually the PPI resolution of the monitor that you are viewing through and has nothing to do with the printing size or the resolution of the image. To get that you multiply the Pixels Per Inch (PPI) by the size of the print required and render at that size.

    http://www.scantips.com/no72dpi.html

    I save all my images at 1000 to 1496 pixels wide at 0 PPI when using IrfanView, or 1 PPI when using Photoshop as it doesn't allow zero PPI. If I want an image for printing I multiply the printed size by 240 to get the render size so a 6x4 image would be 1440x960 pixels. If someone tries to download and print one of my images the largest they will get at 240 DPI would be 4 or 5 inches and if they tried to blow it up to get a bigger print it would just pixelate as there aren't enough pixels in the image to do that.

  • Richard HaseltineRichard Haseltine Posts: 108,093
    Fishtales said:

    The 72 DPI and the 120 DPI are actually the PPI resolution of the monitor that you are viewing through and has nothing to do with the printing size or the resolution of the image. To get that you multiply the Pixels Per Inch (PPI) by the size of the print required and render at that size.

    http://www.scantips.com/no72dpi.html

    I save all my images at 1000 to 1496 pixels wide at 0 PPI when using IrfanView, or 1 PPI when using Photoshop as it doesn't allow zero PPI. If I want an image for printing I multiply the printed size by 240 to get the render size so a 6x4 image would be 1440x960 pixels. If someone tries to download and print one of my images the largest they will get at 240 DPI would be 4 or 5 inches and if they tried to blow it up to get a bigger print it would just pixelate as there aren't enough pixels in the image to do that.

    72, 96, or 120 PPI are arbitrary values applied to an untagged image, as SpottedKitty says.

    You can get DS to calculate the desired size for you - just put size * PPI into the dimesion boxes, e.g.

    6 * 240

    and DS will turn that into the desired number of pixels (pretty well all numeric boxes in DS will do simple arithmetic).

  • ToborTobor Posts: 2,300
    Willanik said:

    Are there any other programs out there that can help me change dpi?   Or even better, is there a way to set render dpi in Daz 4.9 that I am not aware of?  

    *Setting* is the key. As noted, nothing you can do in D|S will set the DPI/PPI) of the saved image. You must do that in an external program. There are many quality free graphic editing tools available, such as GIMP. When changing the DPI/PPI be sure you do not resample the image. Doing so will interpolate additional pixels in order to arrive at the value you've specified.  You simply want the program to update the internal pixels per inch attribute of the image file, and not modify the image itself. The resulting file will still have the same H and V pixels, but will now be tagged with a value useful for printers to print the image in the size you want.

  • WillanikWillanik Posts: 44

    Many thanks everyone.  Spotted Kitty, I could not find the Image Properties tab you mention in my version of Irfanview, but Faststone has it so that's ok (thanks Lyoness).

  • FishtalesFishtales Posts: 6,212
    Willanik said:

    Many thanks everyone.  Spotted Kitty, I could not find the Image Properties tab you mention in my version of Irfanview, but Faststone has it so that's ok (thanks Lyoness).

    It is under the i buttton with the circle around it at the top when an image is open.

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