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Author Topic: render resolution question  (Read 4521 times)

Alpha2

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render resolution question
« on: July 27, 2016, 11:42:11 am »

I'm working on a project that requires me to edit rendered Anima8or images for a printed book, but the generally held rule is that 300 DPI (or in some cases pixels per inch) is the minimum size for a decent print of a non anti-aliased image (which it needs to be for editing purposes since aliased images aren't as sharp). The Problem is every large render I do seems to read below 300 in Photoshop (254 to be exact.) I'd really like the images to be as sharp as they can and raising the resolution after the rendering will just end up hurting the sharpness.

Is there any way to up the resolution of the file output from 254 to 300?

(I know some people say PPI is not DPI but to be on the safe side I've always kept PS files set to that res. to avoid the issue entirely with clients.)
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selden

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Re: render resolution question
« Reply #1 on: July 27, 2016, 07:34:18 pm »

You can use an image manipulation tool to change the DPI specified in the image file to whatever you want without changing the number of pixels in the image file.  I've used Irfanview to do this. I'm sure other programs can do it, too.

You do have to make sure you render the image at a size that you know will include the right number of pixels. e.g. if you want it to be 5" x 8"  on a 300dpi page, render it to be 1500x2400 pixels.

(I assume you're aware that rendering an image at 2x the final image size and then downscaling it usually produces a better quality final result than rendering at the final resolution.)
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Selden

Alpha2

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Re: render resolution question
« Reply #2 on: July 27, 2016, 08:30:03 pm »

No I realize that, but let me see if I can describe the confusion I'm running into...

Lets say I'm working on a comic book. The finished size of a page is (very) roughly about 2100 x 3070 for a 7x10" image at 300 dpi
If I produce a similar image on Anim8or with the same dimensions I get an image that fits the page layout, but at 254.

I wanted to know is there anyway to change the resolution so it just gives me 300 without having to alter the size of the image itself. I ask mostly because the 254 seems like a strange number to land on without a reference for why the program chooses that I'm used to programs like Illustrator or Photoshop that just automatically give you control over the numbers from the outset. Sure, I might be able to squeeze 300 out of the image through resizing but I've run into issues with pixel blurring in the past when clients supply me with sub print quality images which makes me gun shy about using that method and potentially wasting time. It's not so much that I don't want to do the math as it is I'd like to try and remove steps that leave room for error.

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slex

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Re: render resolution question
« Reply #3 on: July 27, 2016, 10:01:44 pm »

Anim8or has a limit of maximum 4096x4096pixels per picture with default 300x300 DPI so that shouldn't be an issue. 
Just be sure to save image as .png file with 100% quality, not as the default .bmp- maybe that makes the problem.

see attached example, can you use it properly as you said?
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Alpha2

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Re: render resolution question
« Reply #4 on: July 28, 2016, 12:22:48 am »

Slex, Actually your PNG comes up in photoshop as 72 pixels per inch. ??? ???

Is this in .98? I use mostly .95 because it crashes on me a lot less. though I guess I could use it for still renders if I can control the resolution the way I'm hoping to.

Edit:// just checked .98 didn't see an option for PNG. is there a trick to doing that? I haven't been around the forums in a while.
« Last Edit: July 28, 2016, 01:27:10 am by Alpha2 »
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johnar

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Re: render resolution question
« Reply #5 on: July 28, 2016, 04:08:14 am »

Quote
Edit:// just checked .98 didn't see an option for PNG. is there a trick to doing that? I haven't been around the forums in a while.
Welcome back.  :)
Quote
Major changes for build 1118:
PNG Support As of build 1118 Anim8or supports reading and writing PNG files.
you got me thinking how long since .png support.
 found it here.. http://www.anim8or.com/smf/index.php/topic,5044.0.html
which was here  http://www.anim8or.com/smf/index.php/board,7.0.html   ;)
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slex

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Re: render resolution question
« Reply #6 on: July 28, 2016, 04:24:31 am »

a very informative chat  :o

1. it's the latest development release of Anim8or - build 1234, it has the option for png.

2. it seems that Anim8or has some unusual values of ppi (dpi is printer resolution), png and jpg saved format gives only 72ppi, bmp has fixed 254ppi quality and that cannot be changed in any way within Anim8or. But, as Selden said you can use Irfanview or Faststone to just open and re-save image(without changing anything) and it would fix it to a 300ppi- Faststone works that way. I think that it doesn't decrease any quality as long as you don't use jpg format


« Last Edit: July 28, 2016, 02:48:54 pm by slex »
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Alpha2

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Re: render resolution question
« Reply #7 on: July 28, 2016, 07:39:36 am »

Okay thanks for the insight, guys. I'll give the latest build a look.

As I recall in the old pre-high bandwidth days, 72 was considered the standard internet resolution for Jpg. When I started looking into this I never found a reason for the 254 output on bmp., it never seemed to have a standard other than being a lossless/uncompressed file format.

I suppose for the time being I'll have to include an extra step to make sure I get the output I'm looking for. Glad to see development is continuing and the community still active and helpful.
« Last Edit: July 28, 2016, 07:46:58 am by Alpha2 »
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selden

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Re: render resolution question
« Reply #8 on: July 28, 2016, 09:17:04 am »

As I pointed out, but you seem to have overlooked, you don't have to leave the dpi setting at whatever Anim8or (or other image producer) uses. You can change the dpi settings of any image without changing anything else about that image.

For example, you can take an image consisting of 2100 x 3070 pixels, one intended for a 7x10" image at 300 dpi but which has internal values of 72x72 dpi, and change its dpi values of 72x72 to be 300x300, leaving the image file otherwise unchanged. 

Irfanview and Gimp are two of the programs with graphical GUIs which include that capability. ImageMagick can change dpi settings, too, if you prefer a command-line utility. ( convert -units PixelsPerInch input.png -density 300 output.png ) I'm sure there are others.

I agree that it would be nice if  the dpi settings could be specified to Anim8or before it writes the image to a file, but it isn't essential if you're willing to add the dpi modification to your workflow.
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Selden

Alpha2

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Re: render resolution question
« Reply #9 on: July 29, 2016, 04:31:44 am »

I didn't over look it Seldon, The answer you gave me was somewhat sufficient, I was just trying to figure out if there was an in-program means for adjusting the resolution so that I didn't need to do it in a secondary program. Again, as I said before I was hoping to avoid situations that could result in errors from having to have an extra step. In the past I've had bad experiences with changing image resolutions where I've lost sharpness before between multiple art programs, so I seek opportunities to avoid the situation.
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Steve

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Re: render resolution question
« Reply #10 on: July 29, 2016, 04:59:11 am »

Alpha2: I wasn't even aware that there was an inherent pixel/inch metric built into those formats, so obviously I didn't add any option to Anim8or to set it.  I'll look into the libraries that I use for .JPG and .PNG and see what I can do. Anim8or just renders pixels :)
« Last Edit: July 29, 2016, 05:00:04 am by Steve »
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cooldude234

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Re: render resolution question
« Reply #11 on: July 29, 2016, 07:12:53 am »

To be honest depending on the printer (the people doing the printing not the machines themselves) you can usually just state what dpi your image is in and send them the image data in a format they accept and they usually will be fine with that. And printing for something like a comic book can get pretty complicated with having to deal with things like bleed margins and stuff. But it really depends on who's doing the printing because there are many different ways to go about it and some companies will only except certain things.
My best advice is ask if they want the dpi included inside the image file.
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ENSONIQ5

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Re: render resolution question
« Reply #12 on: July 29, 2016, 09:49:51 am »

254 on BMPs is probably derived from the number of 10ths of a millimetre in an inch (25.4mm).  ie. 254dpi = 10dpmm.
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Alpha2

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Re: render resolution question
« Reply #13 on: July 29, 2016, 05:55:44 pm »

@cooldude234 Yeah, some printers can throw you for a loop with their requirements, I've been working in book production for a while and I'm still amazed what they can hit you with. The general rule I get from most of the printers I've dealt with is 300 dpi minimum for print comics in CMYK (I believe that's for offset if I'm not mistaken), there are some printers that accept RGB for direct digital printing now (Print on Demand places like Ka-Blam are usually okay with it) but they still suggest 300 pixels per inch. For printing on shirts, sweaters, etc. they may go as low as 150dpi, but only because their inks run a little naturally.

@Steve Thanks for looking into it!
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ENSONIQ5

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Re: render resolution question
« Reply #14 on: July 30, 2016, 02:12:44 am »

To my way of thinking (with minimal print experience) there's two ways to define the resolution of an image:

1) Specifying the size of the image (in mm or inches) and specifying a DPI resolution; or
2) Specifying the number of pixels in the X and Y dimensions.

The DPI figure is of no value if referring to the image by it's X/Y pixels, it will be determined by the printed/displayed size of the image (ie. DPI = X/W where X is the width of the image in pixels and W is the width in inches).  Conversely, a printer requesting a certain DPI makes sense only if the printed size of the image is known, so if you need a 5 X 8 printed image and the printer needs 300DPI you'd need to render an image 1500 x 2400px.  Or am I missing something?
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