ampguy
Veteran
Joe
Joe
digital images have no dpi, it is a term used by imaging programs that have to calculate that based on what they somewhere else think is the actual print size.
72 is common, but so is 96dpi or user defined with most browsers. larger file sizes allow more bits per pixel, and more pixels per real estate mean higher resolution. Firefox 2 and probably IE let you measure a line on your monitor and enter a custom #.
Ray's critiques, IIRC requested ~8" wide photos, at around 80-ish dpi screen display, which means I wouldn't have to use print quality 300dpi sizes for the file upload, but I also wouldn't want to go much more than 1/3rd or so below that before the images start to degrade badly.
Also, I don't think there was anything in Ray's guidelines that excluded the ability to print out the images to critique by taking the best possible file to walgreens, costco, or using your own printer, in any of those cases, you'd want 200-300+dpi.
Joe
digital images have no dpi, it is a term used by imaging programs that have to calculate that based on what they somewhere else think is the actual print size.
72 is common, but so is 96dpi or user defined with most browsers. larger file sizes allow more bits per pixel, and more pixels per real estate mean higher resolution. Firefox 2 and probably IE let you measure a line on your monitor and enter a custom #.
Ray's critiques, IIRC requested ~8" wide photos, at around 80-ish dpi screen display, which means I wouldn't have to use print quality 300dpi sizes for the file upload, but I also wouldn't want to go much more than 1/3rd or so below that before the images start to degrade badly.
Also, I don't think there was anything in Ray's guidelines that excluded the ability to print out the images to critique by taking the best possible file to walgreens, costco, or using your own printer, in any of those cases, you'd want 200-300+dpi.
back alley said:can someone explain this to me...
my understanding is that maximum internet resolution is at 72dpi.
if so, how will a larger file size help for things like photo critiques or lens evals? is there actually more info getting onto the screen?
sorry if this is basic but i don't get it.
many thanks for your patience.
joe
Pherdinand
the snow must go on
Joe, file size has not much to do with resolution, and none of the two have much to do with "72 dpi". The 72 dpi is a "magic"number that does not make any sense. It's about the number of pixels that a normal computer monitor can show (if you put a ruler, or your thumb, on the screen, it will cover 72 pixels).
Resolution/details is, in fact, total number of pixels (i'm talking about the resolution of an minage file, not the resolution of a Leitz lens
) that make up a digital image. It is NOT a dpi value, as Kim says "dpi" alias dots per inch is a pixel density. SHould be called "ppi" in fact, being about pixels and not dots when we talk about images on the screen.
File size, like 150 kbytes, depends of course on the total number of pixels, BUT,m depends on a lot more. Like, compression level. Raw "bitmap" type images take every pixel and its colour values; if there's a 24-bit colour image, this means 3 bytes per pixel. A 5-megapixel bitmap images will be about 15 megabytes. A 8-bit grayscale will be only 5 megabytes.
JPEG images can be compressed to different levels. A compression of 50-80 % can be reached without any visible loss of quality on the image. The more details the image has, the less compressible it is.
Now here's why I agree with Raid's oppinion.
To have a properly viewable image on the screen, it should be at least 800 pixels long on the larger side. Figure 800x500 pixels, that is 0.4 megapixels. 1.2 megabytes thus. To make a 150Kbyte jpeg out of this, one needs a compression of almost 90%. Some images will look like crap, especially the ones with fine gradations like sky, or the ones with very sharp lines; the finest details will be lost.
I usually try to get in the 200K limit but in many cases it is difficult without having visible loss of quality.
Of course, a marvellous shot will be marvellous with a bad resolution as well.
Resolution/details is, in fact, total number of pixels (i'm talking about the resolution of an minage file, not the resolution of a Leitz lens
File size, like 150 kbytes, depends of course on the total number of pixels, BUT,m depends on a lot more. Like, compression level. Raw "bitmap" type images take every pixel and its colour values; if there's a 24-bit colour image, this means 3 bytes per pixel. A 5-megapixel bitmap images will be about 15 megabytes. A 8-bit grayscale will be only 5 megabytes.
JPEG images can be compressed to different levels. A compression of 50-80 % can be reached without any visible loss of quality on the image. The more details the image has, the less compressible it is.
Now here's why I agree with Raid's oppinion.
To have a properly viewable image on the screen, it should be at least 800 pixels long on the larger side. Figure 800x500 pixels, that is 0.4 megapixels. 1.2 megabytes thus. To make a 150Kbyte jpeg out of this, one needs a compression of almost 90%. Some images will look like crap, especially the ones with fine gradations like sky, or the ones with very sharp lines; the finest details will be lost.
I usually try to get in the 200K limit but in many cases it is difficult without having visible loss of quality.
Of course, a marvellous shot will be marvellous with a bad resolution as well.
rogue_designer
Reciprocity Failure
for monochrome images, I can get under the 150 without visible artifacts for images 650px on the long side.
for color, I need to keep them below 500px on the long side to avoid compression artifacts.
Good thing I like B&W
I don't mind linking from an external web location (when that's allowed) - my only issue is that I access quite a lot from work, and the firewall here blocks images hosted on smugmug, photobucket, and flikr. So I don't get to see many of your wonderful posts until I get home (later and later these days).
for color, I need to keep them below 500px on the long side to avoid compression artifacts.
Good thing I like B&W
I don't mind linking from an external web location (when that's allowed) - my only issue is that I access quite a lot from work, and the firewall here blocks images hosted on smugmug, photobucket, and flikr. So I don't get to see many of your wonderful posts until I get home (later and later these days).
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lZr
L&M
Saving for web (72 ppi) i upload 60 to 80 kb files in the gallery, sized 700 x 450 approx.
Bingley
Veteran
I'm a relatively new member here, but the sudden change to a 150kb limit on uploads caught me by surprise, too. I usually work in color negs, and have them scanned on to a CD when I get film developed. I then load selected .jpg files on to my home computer and re-size them using Photoshop or an HP photo viewer program. Previously, simply resizing to a standard size for emailing was sufficient, and I could upload the resized file to a post, where it would appear as a thumbnail that would enlarge to a decent size when you clicked on it. Since the 150kb limit, however, it's been a real struggle to shrink .jpg files down to the limit, and when the thumbnails appear and you click on them they either don't open at all or open and show a tiny image. This is a long-winded way of saying that some relaxation in the 150kb limit would be much appreciated.
Thanks
Thanks
ampguy
Veteran
great info. Pherdinand
great info. Pherdinand
I just measured in firefox under tools/options/content/fonts&colors/advanced, and when I measure the line it puts up, it tells me my monitor is 120dpi, which makes sense, it's a budget ~15" dell that comes up at 1440x900.
However, I try to do the critiques on an old 19" analog monitor since I can fine tune the brightness and contrast with these big huge knobs, and that monitor is like 1280x1024 so probably some smaller dpi.
So don't get too excited anyone, but my thumb on this monitor is going to be more like 200 "dpi"
great info. Pherdinand
I just measured in firefox under tools/options/content/fonts&colors/advanced, and when I measure the line it puts up, it tells me my monitor is 120dpi, which makes sense, it's a budget ~15" dell that comes up at 1440x900.
However, I try to do the critiques on an old 19" analog monitor since I can fine tune the brightness and contrast with these big huge knobs, and that monitor is like 1280x1024 so probably some smaller dpi.
So don't get too excited anyone, but my thumb on this monitor is going to be more like 200 "dpi"
Pherdinand said:Joe, file size has not much to do with resolution, and none of the two have much to do with "72 dpi". The 72 dpi is a "magic"number that does not make any sense. It's about the number of pixels that a normal computer monitor can show (if you put a ruler, or your thumb, on the screen, it will cover 72 pixels).
Resolution/details is, in fact, total number of pixels (i'm talking about the resolution of an minage file, not the resolution of a Leitz lens) that make up a digital image. It is NOT a dpi value, as Kim says "dpi" alias dots per inch is a pixel density. SHould be called "ppi" in fact, being about pixels and not dots when we talk about images on the screen.
File size, like 150 kbytes, depends of course on the total number of pixels, BUT,m depends on a lot more. Like, compression level. Raw "bitmap" type images take every pixel and its colour values; if there's a 24-bit colour image, this means 3 bytes per pixel. A 5-megapixel bitmap images will be about 15 megabytes. A 8-bit grayscale will be only 5 megabytes.
JPEG images can be compressed to different levels. A compression of 50-80 % can be reached without any visible loss of quality on the image. The more details the image has, the less compressible it is.
Now here's why I agree with Raid's oppinion.
To have a properly viewable image on the screen, it should be at least 800 pixels long on the larger side. Figure 800x500 pixels, that is 0.4 megapixels. 1.2 megabytes thus. To make a 150Kbyte jpeg out of this, one needs a compression of almost 90%. Some images will look like crap, especially the ones with fine gradations like sky, or the ones with very sharp lines; the finest details will be lost.
I usually try to get in the 200K limit but in many cases it is difficult without having visible loss of quality.
Of course, a marvellous shot will be marvellous with a bad resolution as well.![]()
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raid
Dad Photographer
From the above [useful] discussion it seems that having a capability to upload images with file size of about 1MB would be reasonable and desirable for the rather limited number of uploaded images in critique sessions.
Raid
Raid
FrankS
Registered User
I noticed this reduction in file size uploads last week when I was posting some Contax stuff. I found that I can post 600X900 whatevers if I reduce the quality (i guess that's compression?) to about medium, on my software (Elements v2), resulting in the necessay file size of less than 150kb.
raid
Dad Photographer
Frank: Yes, but is this really a thing that should happen here?
Raid
Raid
back alley
IMAGES
raid, you make it sound like we are on holy ground.

back alley
IMAGES
my thanks to all who attempted to enlighten me.
i have a brain that very slowly lets small bits of math related info in.
very frustrating...
joe
i have a brain that very slowly lets small bits of math related info in.
very frustrating...
joe
sf
Veteran
FrankS said:I noticed this reduction in file size uploads last week when I was posting some Contax stuff. I found that I can post 600X900 whatevers if I reduce the quality (i guess that's compression?) to about medium, on my software (Elements v2), resulting in the necessay file size of less than 150kb.
You know...this saves money. Less bandwidth, less drive space, less costs to running RFF. Could mean RFF lives longer. Could mean anything.
Then again, it must be nice for the dial-up crowd to be able to read a thread in under 2 hours.
dcsang
Canadian & Not A Dentist
I strongly suggest everyone review the PDF in the following link:
http://www.rangefinderforum.com/forums/showthread.php?t=26335
The author is quite the genius I hear...
Dave
http://www.rangefinderforum.com/forums/showthread.php?t=26335
The author is quite the genius I hear...
Dave
RayPA
Ignore It (It'll go away)
Jorge Torralba said:The paid members get the big file upload in the gallery. I reduced the file upload size for attachments because of the number of files being saved. If it becomes too much of a pain, I will increase it some.
Jorge, any hint of when this might occur? I'd like to update the Critique Guidelines.
Dave: I'll probably drop a link in the guidelines directly to your PDF, if that's OK. It looks useful to those that don't know how to adjust size/resolution.
dcsang
Canadian & Not A Dentist
Sure Ray.. go ahead 
I just wonder why, when we're dealing in terms of pixels and not inches, that people think they need to have larger file sizes simply because there's enough space available.
I've heard every excuse in the book from end users as I moderate a couple photography communities on LiveJournal. From "You're stifling my creativity!" to "I prefer less compression in my images". None have convinced me that, for a fairly large image (i.e. 750 x 500), the file size must be larger than 125kb.
Dave
I just wonder why, when we're dealing in terms of pixels and not inches, that people think they need to have larger file sizes simply because there's enough space available.
I've heard every excuse in the book from end users as I moderate a couple photography communities on LiveJournal. From "You're stifling my creativity!" to "I prefer less compression in my images". None have convinced me that, for a fairly large image (i.e. 750 x 500), the file size must be larger than 125kb.
Dave
raid
Dad Photographer
back alley said:raid, you make it sound like we are on holy ground.
![]()
Joe: I think highly of this site and the people who created and run this site. It is not holy though; once in a while crap happens.
Raid
RayPA
Ignore It (It'll go away)
dcsang said:Sure Ray.. go ahead
I just wonder why, when we're dealing in terms of pixels and not inches, that people think they need to have larger file sizes simply because there's enough space available.
I've heard every excuse in the book from end users as I moderate a couple photography communities on LiveJournal. From "You're stifling my creativity!" to "I prefer less compression in my images". None have convinced me that, for a fairly large image (i.e. 750 x 500), the file size must be larger than 125kb.
Dave
Thanks, Dave.
Basically, you're right. I think it's just a workflow issue. I think a lot of people prefer to do PS work on higher-quality files. I still do PS work after resizing to "72-dpi," but only on high quality files. If I save out to a medium quality file, and want to make a change (PS-wise) I just trash the file and go back to the higher quality version. That means more files/image, which is where I think most of the resistance/kickback comes from. Saving out to a lower quality is just something we'll have to do. I rarely do it myself. I always intend to, but I rarely do.
ampguy
Veteran
Hi Dave
Hi Dave
Which LJ photo communities do you moderate? I know an awesome photographer who posts there sometimes.
Hi Dave
Which LJ photo communities do you moderate? I know an awesome photographer who posts there sometimes.
dcsang said:Sure Ray.. go ahead
I just wonder why, when we're dealing in terms of pixels and not inches, that people think they need to have larger file sizes simply because there's enough space available.
I've heard every excuse in the book from end users as I moderate a couple photography communities on LiveJournal. From "You're stifling my creativity!" to "I prefer less compression in my images". None have convinced me that, for a fairly large image (i.e. 750 x 500), the file size must be larger than 125kb.
Dave
Avotius
Some guy
I just tried to upload to my gallery, that 150 size limit is driving me nuts. The amount of compression and artifacts is simply unacceptable for decent image quality. Please whoever is in charge do something about it, even if its a minor tweek, 200k even, that gives a lot of leway for the images still, 150 is just too small though...if I could pay and uplaod larger images I would but I cant so all I can do is apeal to someone to up the limit a hair.
dcsang
Canadian & Not A Dentist
Avotius said:I just tried to upload to my gallery, that 150 size limit is driving me nuts. The amount of compression and artifacts is simply unacceptable for decent image quality. Please whoever is in charge do something about it, even if its a minor tweek, 200k even, that gives a lot of leway for the images still, 150 is just too small though...if I could pay and uplaod larger images I would but I cant so all I can do is apeal to someone to up the limit a hair.
As the English would say..
Bollocks
150kb is just fine - send me the image to my gmail acct: the(dot)nexus(at)gmail(dot)com
I'll convert and do it for you.
Dave
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