Board index Photography Technical Questions Safe size to display

Technical Questions

Safe size to display

Discuss technical aspects of photography
troron
 
Posts: 219

Safe size to display

Post Tue Nov 11, 2008 5:08 pm


I had a colleague tell me that my pbase photos were "at risk" becasue they were too large and someone could steal them. My first reaction was to ask myself if I really cared if they were used commercially without my permission and I guess I didn't have the strong negative answer of most folks. Not that I want anyone to gain from my images but its not a big thing really.

Well I thought it over and decided to see if I could do something to make my images unusable. I tired water marks and © signatures and all. But I thought later about the following: A computer screen is very low resolution compared to a good quality printer. I save my images at 400dpi in Photoshop and they print so well that I can enlarge way beyond expectations most of the time. But a computer monitor displays at only 72dpi (maybe called ppi). So, why save files with as high quality as you can if you are only going to display them on the internet? In Photoshop the options when saving your psd file as a jpg gives you 12 quality ranges. I tried saving a 1000 pixel wide jpg at all 12 qualities and then looked at them in photoshop again. In fact I uploaded them here and looked at them too. The difference was almost impossible to see on the monitor. However when printed or zoomed in the difference was obvious. The low quality images showed a lot of checkerboarding when zoomed or printed. The high quality images did not.

So that's my experiment. I have no problem displaying 1000 pixel images from jpg file saved at the lowest quality possible becasue they are not usable in any way other than the size displayed. They simply cannot be enlarged or printed with quality.

Any thoughts?

djwixx
 
Posts: 1360

Re: Safe size to display

Post Wed Nov 12, 2008 12:01 am


With regard to the first point I had various photographs that various sources wanted to use for free for their own gain. It struck me as a compliment and seemed quite appealing just to see some of my shots in print. I talked to a friend of mine who does sell photographs and he made a simple point which I stick with. By giving away your photographs you're essentially undervaluing their worth, to the benefit of the receiver, and overall undervaluing the skill of well practiced photographers who make a living selling photographs. If you watch the news or read newspapers you'll probably notice that they are using more and more material from the 'man on the street', so with the explosion of equipment availability and it's capabilities, the need for skilled photographers for briefly used news stories is diminishing. Ultimately the choice is yours, but I suspect full size images are only likely to be stolen by those less scrupulous in their dealings. Saying that, I know some people on Pbase who have had their images stolen and used without permission.

If you're loading images on Pbase for family and friends to download the that's the risk you take. If you loading them for general viewing then full size images will ultimately be a put off to casual browsers who won't wait for it to load and are unlikely to look for a mechanism to limit the image size to their display. For display purposes a great many stick to 800px on the longer side saved at around 80%.

bclaypole
 
Posts: 410

Re: Safe size to display

Post Wed Nov 12, 2008 3:33 am


I don't think there’s any safe size. I posted pictures of my son’s hockey game at 300 pixels on the long side at 72dpi at level 6 quality. A dad printed 4X6's of his son and they looked horrible - to me. He was ecstatic! Unless you put a watermark on them - someone will take them, because something is better than nothing.

dougj
 
Posts: 2276

Re: Safe size to display

Post Wed Nov 12, 2008 3:54 am


Food for thought - DPI is related to printing, while PPI (pixels) is related to display on a monitor. For web use, size the photos in PPI to achieve the desired physical size on the monitor, and the 'quality', or compression setting when saving the images will somewhat determine the amount of original image quality that is displayed. For web use, there is little value in saving an 800 x 800 pixel image with the highest quality (lowest compression) setting as the monitor will not be able to display the detail and the files become large & load slowly for the viewers.

http://www.scantips.com/no72dpi.html
http://www.rideau-info.com/photos/mythdpi.html

troron
 
Posts: 219

Re: Safe size to display

Post Thu Nov 13, 2008 4:11 am


dougj wrote:Food for thought - DPI is related to printing, while PPI (pixels) is related to display on a monitor. For web use, size the photos in PPI to achieve the desired physical size on the monitor, and the 'quality', or compression setting when saving the images will somewhat determine the amount of original image quality that is displayed. For web use, there is little value in saving an 800 x 800 pixel image with the highest quality (lowest compression) setting as the monitor will not be able to display the detail and the files become large & load slowly for the viewers.

http://www.scantips.com/no72dpi.html
http://www.rideau-info.com/photos/mythdpi.html


That is it exactly, Dougj
One cannot see the roughness of a low resolution image on a monitor. And if one steals an image and tries to blow it up or print it they will get pure crap. Too much is made of image size and not enough is made of the image codec algorithms.

BTW anyone with even mediocre Photoshop skills can clone-stamp-away any signature or other mark.


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