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View Full Version : All images should be in a 72dpi JPG format



spec24
01-17-2006, 02:36 PM
I know a lot of people will hate this post, but it scares me when I see this on a site that specializes in graphics software (this is on the NT page for gallery submissions). I don't mean to start any kind of heated discussion, it's just a pet peave of mine when I see it - that somehow a 640 x 480 image at 72dpi is going to be smaller than a 640 x 480 image at 300dpi. Doesn't matter on a computer screen and doesn't change the size of the file or viewing it. It only matters in the world of print. This was a big discussion in graphic design school. :) Now I feel better :thumbsup:

Silkrooster
01-17-2006, 03:16 PM
I see this quite a bit mostly from new users. You are right every once in awhile someplace will ask for submissions with the screen rez and the dpi. I don't know if they just were not paying attention or really did not know that dpi specs are not needed unless the size for print is mentioned with out the screen rez.
Silk

spec24
01-17-2006, 03:46 PM
I guess it bugs me most because while in school I'd have teachers say this - teachers teaching graphic design! - and I'd tell them that it wasn't true and there'd be a large argument and even when they were shown that it was true they doubted what they saw. It's funny how ingrained some things can be :)

Lamont
01-17-2006, 06:00 PM
Yeah, I get the same thing. I just ignore it.

lesterfoster
01-17-2006, 07:26 PM
If it is for the web or video, I use 72dpi or sometimes 96dpi by what ever height and width in pixels that I need. If it is for print. Than you use twice the dpi as what the halftone frequency is. In other words, if your printer is printing at 150dpi for the halftone frequency, than you use 300dpi for the pixels. If your printer is using 120dpi for his halftone frequency, than you output your stuff for 240dpi pixels.

With the exception of webstuf. I always over-sample, because it is ok to have too many pixels-dpi, rather than not enough.

And the JPG thing. That has to do mostly with the web, rather than print or video.

spec24
01-17-2006, 08:07 PM
If it is for the web or video, I use 72dpi or sometimes 96dpi by what ever height and width in pixels that I need. If it is for print. Than you use twice the dpi as what the halftone frequency is. In other words, if your printer is printing at 150dpi for the halftone frequency, than you use 300dpi for the pixels. If your printer is using 120dpi for his halftone frequency, than you output your stuff for 240dpi pixels.

With the exception of webstuf. I always over-sample, because it is ok to have too many pixels-dpi, rather than not enough.

And the JPG thing. That has to do mostly with the web, rather than print or video.

I was just talking about the dpi (not concerned with format), and dpi makes no difference on a computer screen, that's all.

mattclary
01-18-2006, 11:23 AM
When I first saw the title of this thread, I came here to set you straight! LOL!


Excellent point!

When someone tries to argue with you, you should make them tell you how many inches wide a 640x480 image is. ;)

Captain Obvious
01-18-2006, 01:26 PM
When I first saw the title of this thread, I came here to set you straight! LOL!
Haha, me too! :D

spec24
01-18-2006, 08:21 PM
When I first saw the title of this thread, I came here to set you straight! LOL!


Excellent point!

When someone tries to argue with you, you should make them tell you how many inches wide a 640x480 image is. ;)

oh - I had a teacher who tried to explain to my class that an image 640x480, 72dpi on a 15" screen would measure physically the same (as if you put a physical ruler up to the screen) as if it was on a 60" screen. That would be a neat trick. :)

Puguglybonehead
01-18-2006, 09:29 PM
oh - I had a teacher who tried to explain to my class that an image 640x480, 72dpi on a 15" screen would measure physically the same (as if you put a physical ruler up to the screen) as if it was on a 60" screen. That would be a neat trick. :)

Well, assuming the teacher was referring to a 15" monitor at XGA resolution then the resolution of the 60" screen would be a mere 4,096 x 3,072 pixels. (or 5,120 x 4,096 at SXGA) ;)

Hey! I want one of those! :rolleyes:

Limbus
01-19-2006, 03:51 AM
BTW its PPI not DPI :-)

Just trying to be a smart-*** :D

Florian

zardoz
01-19-2006, 03:54 AM
eheh ;D

I'm with you...I used to work on a tv producer and the postprod guy once at my department asked us to always give him our stuff with 72dpi...man, what happened after was ugly...he had 3 or 4 guys almost beating him for that. "It's for tv man!! You're going to get it at 720x576, perŪod! Forget the DPIs"...I don't have to say that now I don't even remember is name...he became "The DPI" guy ...LOL

Matt
01-19-2006, 09:13 AM
I was working on a PDF trying to explain with simple illustrations the difference between screen and print, never finished it though, might have to resurrect it!

Chris S. (Fez)
01-19-2006, 02:00 PM
I was working on a PDF trying to explain with simple illustrations the difference between screen and print, never finished it though, might have to resurrect it!

Please finish it! :) I can think of a couple forums that could make it "sticky."

Kurtis
01-19-2006, 05:24 PM
We understand that the images will display in the same screen space. The 640x480 requirement had to do with working within the website's design.

My understanding is that the 72dpi policy was originally implemented to limit file size, and the attending server space and bandwidth requirements of hosting 1200+ images as a part of the LightWave gallery, not counting the video gallery's requirements. If anyone wants to provide a link to a larger and/or higher resolution image on their own site with their gallery submission, they are welcome to. We can include it in the caption section below the image where we allow artists to post links to their site and email address.

I'm not an expert in this area, so I will ask. Are you saying that a JPG at 72dpi will have the exact same file size as a JPG at 300dpi?

robewil
01-19-2006, 05:32 PM
I'm not an expert in this area, so I will ask. Are you saying that a JPG at 72dpi will have the exact same file size as a JPG at 300dpi?Assuming it's the same image and the same quality setting (you did say jpeg) and if they contain the same pixels (640X480, 720X486, etc), then then the answer is "Yes".

Earl
01-19-2006, 05:34 PM
I'm not an expert in this area, so I will ask. Are you saying that a JPG at 72dpi will have the exact same file size as a JPG at 300dpi?
If they're both 640x480 pixels, yes, the file size will be the same. Browsers ignore dpi since that is only used to convert the pixels to inches.

Kurtis
01-19-2006, 05:47 PM
Ok. Just to be clear...

This is what you're saying:
A 640x480 JPG at 72dpi will be say 150kb
A 640x480 JPG at 300dpi will also be 150kb
Even though they have the same display size and same file size,the 300dpi image will display at higher quality than the 72dpi image.

Is this all correct?

If so, I will be happy to talk to the web team tomorrow about changing this requirement for future submissions.

Twisted_Pixel
01-19-2006, 05:47 PM
Yup :agree:
File sizes are the same.

Just tried and tested in GIMP2 (Poor man's photshop)

Kurtis
01-19-2006, 05:49 PM
Ok. Good. In that case, I'll talk to them tomorrow.

Thanks.

robewil
01-19-2006, 06:00 PM
Even though they have the same display size and same file size,the 300dpi image will display at higher quality than the 72dpi imageActually, that's not really correct. It's the same image, they will look exactly the same, pixel for pixel. The only difference is if you print them at the dpi you set them to, the 300 dpi image will print at 1/4 the size of the 75 dpi image.

Captain Obvious
01-19-2006, 06:01 PM
Even though they have the same display size and same file size,the 300dpi image will display at higher quality than the 72dpi image.
DPI has no bearing what-so-ever when the image is displayed on a computer. The only thing that matters for a website is the actual resolution. When displayed on a computer, the 300,000 DPI image that's 640x480 pixels will look exactly the same as the 30 DPI image that's 640x480.

robewil
01-19-2006, 06:04 PM
I detect an echo in here. :)

Kurtis
01-19-2006, 06:17 PM
Ok. Sorry to be dense here, but I really am trying to understand this. I've never been required to work at anything above 72dpi, so I'm not well versed in the intricacies.

I understand that the original concerns for file size on disk are moot. What I don't understand is, if it has the same file size, displays at the same size, and looks exactly the same, why would it be an issue to leave the 72dpi requirement for consistency?

adk
01-19-2006, 06:17 PM
I just remember one simple thing Ö that monitors donít come with adjustable pixels :)

If you have 640x480 square cars (lets say a 1970ís Fiat) parked side by side in a 2D parking lot you ainít gonna shrink the overall size of the lot by keeping the cars the same size now are you. At the same time because their size is predefined, try as you might you ainít gonna get more of them into that 2D lot unless you have some miraculous way to compress the cars (no rooftop stacking allowed) That miracle is called a Printer :) Itís quite simple really - LOL

Earl
01-19-2006, 06:51 PM
I understand that the original concerns for file size on disk are moot. What I don't understand is, if it has the same file size, displays at the same size, and looks exactly the same, why would it be an issue to leave the 72dpi requirement for consistency?
I guess it's only an issue because it makes it sound like NewTek doesn't understand DPI. Naturally most people really don't need to understand what DPI is, since most people don't deal with it. As mentioned before, since your gallery is online, the DPI of the image makes absolutely no difference to the website or to the quality of the image that is viewed on the website. Pixels are pixels. DPI is a tag (convertion factor) inserted into the file that tells the printer how to convert the pixels into inches. Higher dpi doesn't mean the image is at better quality, it just means that the printer will squash those pixels closer together when printing on paper (the higher the dpi, the smaller the image will print in inches).

DPI is simply a conversion factor. Not a measurement of quality. The only time people associate quality with DPI is when someone says, "Hey this image is 10 inches by 8 inches at 1200 dpi"... because that means that it was made up of 12,000 by 9,600 pixels! Imagine rendering that out in LightWave. :D

Captain Obvious
01-19-2006, 06:53 PM
I detect an echo in here. :)
I typed more than you, of course my post came a bit later! It wasn't there when I hit "reply." ;)



why would it be an issue to leave the 72dpi requirement for consistency?
Unless you plan on printing the images on paper, there is no reason at all to ask for the DPI in the first place.

Kurtis
01-19-2006, 06:57 PM
Ok. Just trying to make sure I completely understand the issue.

Thanks for everyone bearing with me and all the clarification.

UnCommonGrafx
01-19-2006, 07:01 PM
Thanks for being brave enough to ask!!

(Some of us onlookers even found better ways of explaining this to others!)

Silkrooster
01-19-2006, 09:28 PM
DPI is simply a conversion factor. Not a measurement of quality. The only time people associate quality with DPI is when someone says, "Hey this image is 10 inches by 8 inches at 1200 dpi"... because that means that it was made up of 12,000 by 9,600 pixels! Imagine rendering that out in LightWave. :D
10x1200=12000
8x1200=9600
____________
Yep your right! :D
Silk