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EntomanMarch 11th, 2011, 1:29 pm
Northern CA & ID

Posts: 2604
Question: Two images - both clear and similar in size, but if you enlarge them, one remains sharp allowing a closer inspection of markings, projections, etc. and the other goes blurry. Why does this happen and what can be done to avoid it?

Kurt
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
TaxonMarch 11th, 2011, 2:24 pm
Site Editor
Plano, TX

Posts: 1295
Kurt-

It's a function of photo resolution. For example, let's say you take a photo A, which is 5 MB, and then you crop it to photo B, which is 1 MB, and then you reduce its resolution to photo C, which is .2 MB. If you were to load both photo B and photo C, and display both at the same size, and then progressively zoom them in, photo B would remain sharp much longer than would photo C, even though both appear identical before zooming them in.
Roger Rohrbeck
www.FlyfishingEntomology.com
PaulRobertsMarch 12th, 2011, 3:12 pm
Colorado

Posts: 1776
Number of pixels and original image resolution. You can't just add pixels and get more resolution. Lens quality and lighting make a big difference too as to how much info is packed into that image.
SofthackleMarch 14th, 2011, 7:43 am
Site Editor
Wellsville, NY

Posts: 540
Hi,
Check your photo resolutions. As said, the higher the resolution, the more it can be enlarged without it getting blurred. For photo prints, 300 dpi will work, but for viewing online 72 dpi is good. I've seen many photos posted on web sites where the resolution is just too large. They take more time to download or might appear humongous on your screen. I always make two versions of my photos-one for online viewing, the other for print if I think I'll need it.

Mark
"I have the highest respect for the skilled wet-fly fisherman, as he has mastered an art of very great difficulty." Edward R. Hewitt

Flymphs, Soft-hackles and Spiders: http://www.troutnut.com/libstudio/FS&S/index.html
PaulRobertsMarch 14th, 2011, 1:59 pm
Colorado

Posts: 1776
Yes, as Mark said, 72dpi for screen, 150dpi for color printer, and 300dpi for photoprint quality.

For the screen, most sites have a suggested width. I usually go 600 pixels for horizontal images and 425 for verticals.
EntomanMarch 15th, 2011, 11:51 am
Northern CA & ID

Posts: 2604
Hi guys,

Well, pixals and other factors at the camera have been mentioned, so has mbyte file size which is a storage issue, and finally the dps required at the monitor for proper display. Can somebody tie it all together?

Thanks,

Kurt

P.S. I love what Jason has done with his photos in the bug section. His little magnifying glass in the corner allowing a closer look for assistance in identification is a great feature.
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
SofthackleMarch 15th, 2011, 12:39 pm
Site Editor
Wellsville, NY

Posts: 540
Hi Kurt,
For display on a computer screen, all you need is the correct size you desire of the photo at 72 dpi. In other words, if I shoot a photo with a 10 megapixel camera, and the raw image is, say 50 inches wide by 34 inches high at 72 dpi, it can be reduced or cropped to the size you desire keeping the dpi at 72. It should appear in focus on a monitor.

It can also be reduced and the dpi increased. When you make a photo smaller than the raw image, you can gradually increase the dpi. So let's say you take the above photo and decrease the measured size by half, you can then increase the dpi size by half. So now the photo is 25" X 17" at 150 dpi. Decrease again by half, and you have a photo that is 12.5" by 8.5" at 300 dpi-this is enough to make a good quality photo print.

You can decrease/crop the size without decreasing the image dpi for online viewing. The size is up to you. Notice, I'm not increasing the SIZE width and height, just decreasing. The same goes for increasing dpi, you can do this as explained. Again, I'm decreasing measured size while increasing dpi.

Of course a smaller photo, say one at 450 dpi at 6" x 4" can be increased in measured size, but the resolution must be decreased, otherwise you run the risk of pixelization. A 6" X 4" could be increased, perhaps to 7" X 5" to 300 dpi, and it'd still be good for photo printing. You can also make this 6 x 4 photo to 8" X 10" at 72 dpi for online viewing.

To my knowledge, if the photo is viewed on a monitor, as long as it is at 72 dpi, it should be in focus. It may appear smaller on monitors which are set at higher pixel settings, but it should be in focus.

The standard monitor settings are 800 X 600, 1024 X 768,and so on up. As you increase the settings, the photo will look smaller on the screen, but it should still be in focus, not pixelated.

Cameras with higher mega-pixels offer photographers more latitude in print size. The higher the mega-pixel, the larger the print possibility.


I hope I've not over complicated it for you. Good photo editing software is a real advantage. I believe Picasa is a free software that might help. you can download it, online. Adobe PhotoShop Elements is also very good, but it must be purchased, and it an be at reasonable prices.

Mark

"I have the highest respect for the skilled wet-fly fisherman, as he has mastered an art of very great difficulty." Edward R. Hewitt

Flymphs, Soft-hackles and Spiders: http://www.troutnut.com/libstudio/FS&S/index.html
BcvizinaMarch 15th, 2011, 6:58 pm
Northern Michigan

Posts: 30
I think one of your photos might be slightly out of focus. It would only show up if you enlarged it.
EntomanMarch 16th, 2011, 2:18 am
Northern CA & ID

Posts: 2604
Mark - Posts are tough for explaining a complex subject. I just want to push a button (or make a wish) and it happens, right? Anyway, I'll use your post for reference as I learn "Greek". Thank you and everybody else very much for the input.

Regards,

Kurt
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman
EntomanMarch 17th, 2011, 1:15 pm
Northern CA & ID

Posts: 2604
Thanks for the input from everybody. Posted my first photos today, and there's no way I would have even tried without your help. Also to Jason who I bugged a lot, but was always helpful as I bounced off the walls.

Regards,

Kurt
"It's not that I find fishing so important, it's just that I find all other endeavors of Man equally unimportant... And not nearly as much fun!" Robert Traver, Anatomy of a Fisherman

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