A Digital Printing Network
Minimum requirement's for photo's
I have been doing cut vinyl for several years, but the Versacamm is my first foray into wide format printing.
What is the minimum quality needed for photographs and art for large prints. I recently printed a large banner that turned out great, the customer provided a nice large clean 150 dpi photo that was as simple as saving as an eps and running the job.
I have a customer that has sent me the artwork for a banner she has had done before and it is not going to work, it is 96 dpi and fairly small. When I talk to the customer how do I explain what I need from them? I will be printing this in a couple different sizes, the largest being around 28x40 or so.
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itworks.jpg, 30 KB
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Replies to This Discussion
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Permalink Reply by Admin on -
I always tell them a minimum of 72 PPI at print size. I have a sample that I can physically hand them that they can see the different PPI settings and how it will look. You can download it here: http://dl.dropbox.com/u/18923867/DPI%20PPI%20example.eps
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Permalink Reply by Dennis Dunning on -
Here is an opportunity for me to learning something new. I recently took a few photos for life-size wall graphics using an 18 megapixel Canon EOS Rebel camera set at high quality (5184 x 3456 pixels). The resolution of the resulting photos was 72 dpi, which would be way below 72 at full size - in fact the faces in the photos look grainy. Why was the dpi (or ppi) on my photos so low even though I was shooting at the high quality mode?
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Permalink Reply by CYW on -
Dennis, I think you're getting pixels and resolution all mixed up
A 5184 x 3456 pixel image should actually be 72 inches by 48 inches
As a general rule, you should be concerned with the pixels in an image more than the resolution.
I think folks get scared when they see that 72 dpi number and I think it's because we've all seen more than enough 72 dpi images the size of a thumbnails with very, very low pixel counts.
What you have is an extremely large image (pixel count).......the resolution is basically inconsequential.
Like Steven said, 72 dpi at PRINT SIZE is what's important.
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Permalink Reply by Admin on
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Dennis - try printing the file I linked above - it will show you the difference between PPI (Pixels per inch) and DPI (Dots per inch) Regardless of the size of the photo, it will be dependent of the PPI at print size of the picture you are working with. Some 2 MB files work great while other 15MB photos are horrible when enlarged to print size.
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Permalink Reply by Dennis Dunning on
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I recognize the file that you linked from the vehicle wrap class you helped present. The issue of resolution is beginning to remind of that for color management, it's not (as Ross Perot said when running for president) "just that simple". The reason I'm so interested is that I took photos of tennis players with the intent of creating life-size wall graphics with Seramark. I took the photos at the highest-quality setting. When I examine the properties for the photos they are 5184 x 3456 pixels and 72 dpi. When I set the height of the photos in Corel to about 6' tall, the faces of the players are grainy. So, I was trying to understand why, given that most online websites indicate the photos taken with an 18 megapixel camera at a high quality setting should provide "excellent" results my results were less than excellent. I guess my question is where did the 72 dpi property in my photo come from and is it relevant to this discussion given that the photos are also defined by the number of pixels. I'm confused.
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Permalink Reply by Dennis Dunning on
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OK folks, The Admin (Steven Jackson) gave me an education, again. To help others benefit from my education, to reinforce it for me, and to show Steven that I understood what he explained, I agreed to write down what I learned.
After importing a photo into CorelDRAW, open the Object Properties docker and click on the Bitmap tab, which displays properties of the object (in this case the photo). With the height of my photo set at 10" in CorelDRAW, the size of my photo was 3456 x 5184 pixels and the resolution was 518 x 518 dpi (which is relatively high). With the height of the photo resized to 69" (closer to life-size), the size of the photo remained at 3456 x 5184 pixels but the resolution was reduced to 75 dpi, the minimum considered acceptable for printing. However, the face of my tennis player still looked grainy.
The problem was in part that the height of the tennis player from the tip of his feet to the top of his racquet (extending above his head) was 51" (about 72% of the total height of the photo, which meant that 28% of the photo was space above and below the player). Removing the 28% of the photo above and below the player and resizing him from 51" to 69" (closer to life size), dropped the resolution of the photo to 55 dpi: ergo, a very grainy face. Added to that, was probably some movement of the tennis player's head during his swing.
The take-away from this for me is twofold: 1) get closer to my subjects so that they take up more than 72% of the height of the photo and 2) limit the height of the resized photo to that which provides an acceptable looking resolution (which is likely to be greater than 75 dpi minimum). For those of you who already knew this, I hope you didn't read the whole reply.
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Permalink Reply by Dennis Dunning on
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Here is a follow-up to the reply I posted above. I used my best lens, put my camera on a tripod, maximized the size of my subject in the field of view, and made my subject stand still (in other words, I staged the photos of my tennis player to minimize blur do to movement). I imported the file into CorelDRAW and expanded the photo to near life-size (I wanted the dpi to be at least 72). The result was noticeably better than my previous results. However, you need to stand back from the image for it to look acceptable, which is how most wall graphics will probably be viewed. Where on-line websites indicate that photos taken with an 18 megapixel camera produce excellent results for life-size wall graphics, "excellent" is clearly relative.
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