Still can't figure out the resolution questions

Discussion in 'Large Format Inkjet Printers' started by uno_sir_clan, Apr 14, 2011.

  1. uno_sir_clan

    uno_sir_clan New Member

    Joined:
    Apr 2011
    Messages:
    2
    Location:
    US
    I work usually with web design so when it comes to resolution in respect to printing I get a little lost.

    I have Designjet z3100 24 in. In User's Guide it states that my printer's "best" rendering resolution is 1200x1200 (dpi) and the printing resolution is 2400x1200 (dpi).



    Quesitons:

    1) What's rendering resolution and what's printing resolution.

    2) If I want to print a banner 24in by 60in in the best quality possible, what the resolution of my image should be.

    3) What's the difference between image size and document size (in photoshop), and how it relates to resolution.



    I hope I can finally get these printing resolution questions figured out, because right now I am very confused.

    Thank you guys
     
  2. Michael4

    Michael4 Senior Member

    Joined:
    Jan 2011
    Messages:
    174
    Location:
    Jersey City, NJ (USA)
    In Photoshop: Image size will allow you to set your resolution (ie 300DPI - 600DPI Etc) Your resolution must be set before you begin your design. Changing it to a higher resolution after the design is made will result in pixilation (IE you designed something for web at 75DPI it cannot be changed to)

    You want resolution at least 300Dpi for any printing. for a banner , 600 may be a better bet. Its also better to use a Vector program like Illustrator/Corel/Indesign if you have one...

    The document/canvas size is how big the image will print (in inches, Millimeters etc)

    Rendering resolution refers to the image as its RIPed by the printer. Print resolution is the max amount of DPI/LPI a printer can produce. My CanonIP can print up to 1200dpi (dots per inch)
     
  3. uno_sir_clan

    uno_sir_clan New Member

    Joined:
    Apr 2011
    Messages:
    2
    Location:
    US
    Thank you for your answers. Also, so image size (in px) directly dependent on resolution (dpi) and visa verso?
     
  4. Michael4

    Michael4 Senior Member

    Joined:
    Jan 2011
    Messages:
    174
    Location:
    Jersey City, NJ (USA)
    Good question actually. Im going to answer 'yes' to that question.
    I do believe they are independent.

    The Pixel size still reflects how big the image will be in size. Only in this case it is how big the image will appear on screen rather how big it will print.
    This is more for web graphics. you can have a low print res (75Dpi) but the image will still appear great on screen. Save that same image for print and its going to print terrible.

    You could have a high rez (300Dpi) image in pixels, but it would take forever to load on the web, and will still print pretty small.
    Its best to set pixel sizes for web items only , and use inches/MM for print items with a decent dpi. You can always down save (change to pixels and lower your dpi) your print items for the web
     
  5. BillO

    BillO Member

    Joined:
    Mar 2011
    Messages:
    35
    Location:
    midwest
    I don't know if I can add anything to Michael's response, but the issue of optimal ppi (pixels per inch, though it's commonly referred to as dots per inch even though the two are different) has been on my mind for a different reason. So here are my 3 cents (with inflation.)

    In photoshop, you can choose to specify it however you like, but the (raster) image size = dimension x pixels per unit of that dimension = total pixels. So you can do 300 pixels per inch and 24 inches wide, or you can specify in pixels 7200 pixels. Either way you'll have 7200 pixels each of a given color (24" x 300/" = 7200 square total in the x direction.)

    DPI used to have to be much higher than PPI as you only had C, M, Y, or K dots of ink sprayed to try and reproduce any color of pixel. Ink doesn't "mix" as easily as light but instead lots of small dots are used to make you see the color of the pixel. You might have 300 pixels per inch, each of a unique color. It might take 1200 dpi to achieve this. So each pixel takes 16 dots of c, m, y, k, or absent (white) to create the color of that pixel. Now however with inkjets, we have 8, 10, 12 colors so you need less dots per pixel to render the color of that pixel.

    I'm intrigued what HP means by rendering resolution. Do they mean that you get a visible advantage working as high as 1200 ppi for a printer which runs at only 1200x2400 dpi but with the additional colors??? I've never worked over 600 dpi for inkjet output to date.

    Following this thread with interest.

    P.S. another intriguing thing to me since web res was brought is that historically prints have been much crisper than monitors. Now however, we see monitors coming a long way. Somehow a monitor is able to transmit light to our eyes and make 96 to 120 ppi look good, sharp, crisp as rgb "light" additive put out by the lcd monitors, yet the same resolution printed cmyk subtractive looks pixelated when viewed from the same distance and tends to look blurred if you try and resample it higher (when you don't have higher resolution to work from.) In theory it seems like we should be able to resample up as well as the monitors trick our eyes into seeing the low resolution image, but it doesn't seem to be the case.

    Sorry if I've answered your question with a rather rambling post and more questions.
     
  6. Michael4

    Michael4 Senior Member

    Joined:
    Jan 2011
    Messages:
    174
    Location:
    Jersey City, NJ (USA)
    No rambling at all. A lot of good points in there. Interesting point about the monitor vs print. I do remember monitors having the ability to display few colors and having very large pixels. I also remember 7.5in floppy disks. That brings me back.

    But the addition of RGB color mixed with white light/tubes has made an enormous improvement on the way we see images on screen. I take it for granted these days
     

  7. Ibex

    Ibex New Member

    Joined:
    Sep 2011
    Messages:
    3
    Location:
    seattle United States
    DPI can be a bit tricky. Just try to read around a bit. Try this article out