Hi again. I have started using P7 to render my production work and have come across a problem.

I generally render with the resolution set to 2048 pixels per inch.

In P6 I used to set my Max Texture size to 2048 also.

I understand In P7 Max Texture size is handled automatically.

Now, I have just rendered an image set to 2048 Resolution but it has rendered at 72 Pixels per inch.

I'm not sure how to rectify this as the finished image quality is noticably reduced.

Any ideas.

That P7 only outputs to 72 dpi is a known bug. See the other threads about it for work arounds.

Ahh!..... I see!.... Good!...... Right!....errr... back to P6 then.

There something that bothers me for a long time: Can someone explain that dpi is so important for rendering?
What's the difference between a picture that's 1200x1200 pixels, 24bit, 72dpi or a picture 1200x1200 pixels, 24bit, 300dpi? Is there more information in the picture or is it just a switch?

As far as I am concerned it makes a hell of a difference, especially on close up work. 

The higher resolution gives my images more detail eg, individual strands of hair and skin detial are more visible.

I never have to print but I gather 300 DPI is important for print quality.

Quote - What's the difference between a picture that's 1200x1200 pixels, 24bit, 72dpi or a picture 1200x1200 pixels, 24bit, 300dpi? Is there more information in the picture or is it just a switch?

There is absolutely no difference. Many people don't understand what dpi even means in CG so they start thinking a higher dpi means higher quality. This is just not true. 72 dpi means that when printed (on paper) the printer will use 72 dots per inch to print the image. 300 means it will use 300. In both cases the size of the image printed will change, but always at the same quality of 1200x1200 points.

ie a 1200x1200, 300 dpi pic will print at 1200/300 or 4 inches by 4 inches. A 72 dpi one at 1200/72 or 16 x 16.

The only way to get higher detail is to increase the rez itself, dpi does nothing.

I don't know about any difference as regards DPI, but there is a significant difference between 72  Pixels per inch and 2048.

Having reread the original post I see "bopperthijs" was actually using the unit of DPI, so my post was probably flawed. But I still maintain that using higher Pixels per inch settings when rendering, providing the max. texture size is set accordingly will produce more detailed renders.

Which was in essence what I was trying to say :op

Well we could discuss semantics all day but anyway :)

Anyone wanting more complete info should try this (how did we ever get anything done before wiki):

http://en.wikipedia.org/wiki/Dots_per_inch

:o)    Or we could use a direct qoute from the Poser 7 Manual, Page 64, which says:

***Resolution:

---

 72DPI is normal for screen resolution images and is suitable for images you intend to distribute online.

 300DPI is appropriate for most print functions.

 1200DPI is used when you need extreme detail.  

quote:
    *providing the max. texture size is set accordingly will produce more detailed renders.

*That could make the difference! In P6 you could set the max texture size yourself, and that isn't possible in P7. It probably tells the render engine at what resolution you want to print, if that doesn't work it's a big bug!

But on the other hand, you could also set the dpi is P6, so that doesn't make much sense!
Well, I'm trying to figure this out, I give the results later.

You have a printer, whose resolution is fixed at, say, 72 dots per inch (DPI), a dot being the smallest paper space that it can fill with its ink or toner. Then you have an image set up to 300 DPI, fine. Do you think your printer would produce a 300 DPI image? I don't think so :) DPI is significant if, and ONLY if, you are setting your RENDERED image to be X inches to Y inches WHEN PRINTED; really, it's only an helper to find the correct render dimensions in pixels for the desired print dimensions in inches. If you have Photoshop (or even GIMP, the idea is the same) you can test this: - set units to inches, then set up a new image 5x5 inches with a 300 DPI resolutions, then switch units to pixels and note the dimensions of the image. - do the same, but now set your resolution to 150 DPI, and note the new numbers after switching to pixels again: do they are exactly half of the previous ones? One pixel on the video screen corresponds to one dot of the printer device, and while screens have about 72 pixels for every inch, printers can have (and DO have) much higher resolutions, up to 4000 and more dots per inches in professional (and costly) devices. When you are watching a 10x10 inches image on your screen, you are really seeing a 1072=720 pixels image; to print this 10x10 inches image on a 300 DPI device, you must have a dimension in pixel of 10300=3000. You can set it directly, but the inches+DPI units can help you to find the correct dimensions in two easy steps, if you want. I said: INCHES+DPI...if you are working with pixels as units, DPI is only a screen filler :D

Quote - That could make the difference! In P6 you could set the max texture size yourself, and that isn't possible in P7. It probably tells the render engine at what resolution you want to print, if that doesn't work it's a big bug!

Err... no, it just means that any texture bigger then the max texture size will be sized down to max texture size... Poser 7 doesn't need that setting as it uses other means to reduce memory usage and doesn't need to downsize textures so they all fit into into memory.

Oh well, then there's the texture resolution to take into account, but it has nothing to do with DPI settings in the image. As other said, your max texture dimensions would be set according to the image size; it has to be done in pixels, remember that you are really working on a screen, not on a printer. On the other side, Poser7 doesn't even seems to use that feature so you're OK everytime, if you use marketed textures which seems to be always 4000 up in size (more than sufficient for a good professional work, as it's uncommon that the textured object is larger than that). P.S. - On a side note: not really sure, perhaps there is an image property that tells the printer what DPI setting it must use, and it's triggered by the DPI setting on the rendered image. I don't think so, but I'm not a graphic editor and I know that every image can carry a load of info in itself, from date/time of creation to adjustment levels, so everything can be........

Quote - You have a printer, whose resolution is fixed at, say, 72 dots per inch (DPI), a dot being the smallest paper space that it can fill with its ink or toner. Then you have an image set up to 300 DPI, fine. Do you think your printer would produce a 300 DPI image? I don't think so :) DPI is significant if, and ONLY if, you are setting your RENDERED image to be X inches to Y inches WHEN PRINTED; really, it's only an helper to find the correct render dimensions in pixels for the desired print dimensions in inches. If you have Photoshop (or even GIMP, the idea is the same) you can test this: - set units to inches, then set up a new image 5x5 inches with a 300 DPI resolutions, then switch units to pixels and note the dimensions of the image. - do the same, but now set your resolution to 150 DPI, and note the new numbers after switching to pixels again: do they are exactly half of the previous ones? One pixel on the video screen corresponds to one dot of the printer device, and while screens have about 72 pixels for every inch, printers can have (and DO have) much higher resolutions, up to 4000 and more dots per inches in professional (and costly) devices. When you are watching a 10x10 inches image on your screen, you are really seeing a 1072=720 pixels image; to print this 10x10 inches image on a 300 DPI device, you must have a dimension in pixel of 10300=3000. You can set it directly, but the inches+DPI units can help you to find the correct dimensions in two easy steps, if you want. I said: INCHES+DPI...if you are working with pixels as units, DPI is only a screen filler :D

 

I entirely agree. But if you look back the original question wasn't printing related. The actual question was:

"There something that bothers me for a long time: Can someone explain that dpi is so important for rendering? !

As regards rendered images, you do get more detail per square inch with Higher DPI settings in your "Render Dimensions" window, providing the Max.Texture setting in "Render Settings is suitably high.

Quote - As regards rendered images, you do get more detail per square inch with Higher DPI settings in your "Render Dimensions" window, providing the Max.Texture setting in "Render Settings is suitably high.

Sure, more details when printed, but the rendered (=on screen) image would be the same, whichever DPI you use. From what I know DPI isn't used for textures, and if you look closer to the render dimensions dialog you can even see that it is greyed out if you use "match preview window": as this is only a way to say "render at that dimension in pixels" and the render is always visible in the preview window whichever dimension you use, can't see why it's greyed, if it's true what you say... Just on the topic at hand, though, I've noticed a worse image quality in the P7 renderer against P6, both in lightning and in texturing; for the latter I can blame texture filtering...but for the lights??? So, I think the problem lyes elsewhere than simple DPI settings...

Well, I did some renderings which I will post here, but as far as I can see doesn't make the dpi settings any difference, what makes a difference is the texture-filter settings which has been discussed in another thread. I made a close-up of a V4-eye with the hires-texture which = 4000x4000 (for the face), not other extra's: just the standardlighting, used final automatic settings in P7 and manual settings in P6, with texturefiltering and maxtexture of 2500, (with 2gb on a PC is for me the max) and without texturefiltering and a maxtexture of 4000. I did different with 72dpi and 300dpi, but I didn't see any difference so I won't post that. First the P7, which I think is the second best  because its slightly  blurred (probably by texture filtering)

second the p6 textured filtered and maxtexturesize 2400pixels, I think this is the worst

And at last the P6 no texturefiltering and maxtexturesize of 4000pixels,
In my opinion this the best.

I'm still wondering why E-frontier took out the maxtexturesize filter, It gives you much more control over the result. I discovered some jaggies in the brow, but they were also on the original texture. For that kind of detail you need even bigger textures.

Try again, slightly compresse, hope it didn't influence the quality too much.

ANd again, now the right file :blushing: :cursing: 

*There something that bothers me for a long time: Can someone explain that dpi is so important for rendering?

*DPI means Dots Per Inch, and is a term used in Printing.  It's a measure of how much ink is used while printing.  An image that is rendered at 300DPI actually has 300/72 more pixels than an image rendered at 72 DPI.

In other words let's say you render an image of 1000 x 1000 pixels at 300 DPI.  If you then open photoshop; load the image, and convert it to 100 DPI, then the converted image is now 3000 x 3000 pixels(without any loss of detail)

You have a printer, whose resolution is fixed at, say, 72 dots per inch (DPI), a dot being the smallest paper space that it can fill with its ink or toner.
Then you have an image set up to 300 DPI, fine.
Do you think your printer would produce a 300 DPI image? I don't think so :)

and

I entirely agree. But if you look back the original question wasn't printing related. The actual question was:

You don't have a printer set to print at 72 DPI.  72 DPI is the resolution your monitor uses.  A cheap inkjet printer, now a days, is at least 720 x 720 DPI - 1440 x 720 DPI, or more.

Quote - In other words let's say you render an image of 1000 x 1000 pixels at 300 DPI.  If you then open photoshop; load the image, and convert it to 100 DPI, then the converted image is now 3000 x 3000 pixels(without any loss of detail)

Ehr...isn't the other way around? If you decrease DPIs in Photoshop, the image is smaller than before (obviously, I'm assuming that you are not changing the overall dimension of the PRINTED image). > Quote - You don't have a printer set to print at 72 DPI.  72 DPI is the resolution your monitor uses.  A cheap inkjet printer, now a days, is at least 720 x 720 DPI - 1440 x 720 DPI, or more.

It was only an example :)

Quote - ANd again, now the right file :blushing: :cursing:

LOL :lol: :lol: :lol: Well, I don't see too much of a difference, at least not while I open the images in three separate windows and I switch through them. For what I'm seeing, every subtle difference is going to be flattened by the first adjustment you'll do later in postworking, so...I'll call you HawkEye from now on :biggrin:

I have to say, I just tried the same thing. I rendered (in P6) a close up of a character I am working on using full firefly settings in both 72 Dot Pixels per inch and then again with 2048 Dot pixels per inch.

I saw no noticable difference.

However, on another scene where one of the charcters is sitting in the background there is definite improvement. Especially the detail evident in the hair.

Based on my findings I would like to change my earlier statement where I said Higher DPI's are especially better for close up renders. It would seem that they come into their own when hires textures are further away from the camera. 

If you think about it this makes more sense and could be what the poser manual is referring to when it says 1200DPI = extreme detail.

The extra DPI making far off textures more detailed.

If the image format your saving to suppports a DPI value, then you can change this value in your 2D graphics app.

For PSP9, it's Image | "Resize ...", uncheck "Resample using" and then just set the desired DPI in the "Print Size" section.
I believe PS allows something similar.

Quote - If you think about it this makes more sense and could be what the poser manual is referring to when it says 1200DPI = extreme detail.

The poser manual is written by a bunch of brain dead monkeys, or so i would state if i didnt like monkeys. If the dpi is making any change (and you should verify this in PS with a difference comparison) it is likely modifying other settings not because of dpi itself.

To a renderer, dpi is meaningless, Firefly (and every other render engine out there) only deal with pixels. They dont understand any real world unit of measurement like inches or anything. All they do is take one pixel in a file, render it out and then move to the next. What printers do with each pixel is where dpi is used.

quote:

*Well, I don't see too much of a difference, at least not while I open the images in three separate windows and I switch through them.

*That's my point : there isn't much difference, only when you compare the three renderings in Psp or similar and you zoom in , you can see some difference. I did all the renderings in both 72dpi and 300dpi but that doesn't give any difference at all. Perhaps you noticed I didn't use any anti-alias filtering   (you can see it on the lower eyelid), when you use that all the subtile differences will disappear, because the picture will be slightly blurred.

Considering the 72dpi  setting: that isn't the setting your monitor uses, dpi is meaningless for monitors. 72dpi was the standard for the first  black and white matrix printers about 20 years ago. This standard has become a little useless nowadays.

The amount of times this has come up should warrant it being a sticky! :)
A 1200x1200 pixel image has the same number of pixels no matter what the dpi (which should really be ppi on screen). The dpi (I'll use that term instead of ppi as that's what everybody is used too) only comes into effect when printing, as a 1200x1200 image printed at 72dpi will be around 16" square, and look like a picture from a newspaper that has been greatly enlarged, whereas the 1200x1200 image printed at 300dpi, will be a 4" square picture that looks very good quality. 
It's not hard really, but if you absolutely need a picture from Poser7 at 300 dpi then just multiply your finished size in inches and multiply by 300, and use those values as your image size. IE, 8" by 10" would be 8x300 = 2400 by 10x300 = 3000. Job done, easy.
If you are rendering large pixel size images in P6, then setting too low a max texture size could impare quality as P6 will downsample the texture to the dimensions you specify. Also, texture filtering can blur textures too. So, for detail in your images, a large pixel dimension is required, not a large dpi setting.
Blimey I went on a bit there :)

Oh, and Happy New Year from England!!

If you use the correct resolution for your monitor, and you want to view an image at an aproximate dimension in inches, you can use the 72 DPI rule, you are not that far apart. Correct resolutions are 800600 for a 15", 1024768 for a 17", 12801024 for a 19". Then there are blockes like me that uses 1152864 in a 17"....obviously, I must change the numbers if I want to see how big would be my image when printed. I mean, that is only a basic rule, and EVERY photo manipulating program uses that as basic setting. And yes, it's almost meaningless, but it's a basis :)

Did anyone see my other post?

" A 1200x1200 pixel image has the same number of pixels no matter what the dpi "

Raven - If you are talking 300 DPI; and referring to 3" square inches of print, then you are talking about a lot more pixels than if you were referring to that same 3" square inches of print at only 72DPI.

In other words the data that defines the pixel is there to be defined by the literal Size and DPI attributes an image holds.

It work the other way around, a 1200 x 1200 pixel image will print at 4" x 4" if it's set at 300 DPI, and will print at 12" x 12" if it's set at 100 DPI.

Put another way, the DPI setting controls the print size.