Digital Art Zone

vindazi - 18 September 2012 11:35 AM

David Brinnen - 18 September 2012 11:32 AM

I think you are confusing Peter’s tutorial with my video. My video is an overview of the Pan h and Pan v controls.  It was not intended to be a direct guide to producing large renders.  However, if as I said, you could provide me with the dimensions you want your final render output at then I could provide you with the steps needed to render at that size - using Pan h and Pan v.

Sorry about that.

I want to do 18x12 at 200 dpi.

would need to know, final output size.  pixels x pixels.

The reason I specified pixels by pixels because without knowing your printer I would not know how many dots were required to represent one pixel value.

As I was saying to Erich just the other day…

>> By the way, don’t let them talk to you about dpi - it is a nonsense
>> for printers.  Only deal in pixel resolution.
>>
>> I have had this discussion so many times now, I’m really fed up of it.
>>
>> DPI is dots per inch.
>>
>> A dot is not a pixel.  A pixel’s information may need many printer
>> dots to make the same value of information.
>>
>> If you are doing print reproduction, you need to know how many pixels
>> by how many pixels the printer is competent to reproduce.
>>
>> To start with the 72 dpi is arbitrary, you can change it to 300 dpi
>> in paint shop pro.  The difference is when printed the image will get
>> smaller.  It has the same number of pixels for output.
>>
>> What is the output?  If print, you need to get someone to run some
>> print tests.

I think I am going to beg Horo to write a little explanation for this since he has done such print tests and we are forever running into this dpi issue.  Just, I think because it is shown in the render to disc options, it is given credence - also printers who should know better give it credence.

and more >>

You cannot convert a pixel directly into a dot (well should not)

Suppose a dot on a printer is either black, yellow, cyan or magenta.

And to get the colours, the dots are staggered.  So the calculation is how
many dots are required to make the same information value as one pixel?

Otherwise you are just wasting pixels - wasting information and render time.

Suppose DPI B,Y,C,M on or off, 1,1,1,1 max values.  RGB 255,255,255 you need
a more 1,1,1,1’s to express the same information as 255,255,255 will.  So
DPI will be much higher than PPI.

DPI is dots per inch not PPI pixels per inch.

The printers should be able to say, how many PPI is appropriate, but in my
experience, printers can’t be [bothered] to think about this problem and as a
result over specify and talk in DPI.

<<

So your dimensions would give me a total of printer dots by printer dots, but I don’t have any conversion for how many dots make a pixel.  If you choose 1:1 you will have to make huge renders and then be throwing away 50% or more of that information when you print.

Do you see how wasteful this could be?

I can give you a specific example from having had professional prints done.

A 7200 x 5400 pixel image can be reproduced on a good colour printer at A2 size - and it will look very good and withstand close scrutiny.

A2 ~ 420 x 594 mm

Could easily get away with half that resolution if it was hung on a wall.

Well this complicates things a bit. I don’t print these myself. I send them to one of many pro-printing houses, depending on where they are to be shown. They have various printing equipment. They specify the types of files they want, i.e. jpg, tiff, psd etc. So I do not know and can not know the printer.

Can’t I output to a standard file format in Bryce?

Of course you can.  That’s my point, dpi is something printers like to bang on about.  What Horo did was produce a series of test images at different resolutions pixel x pixel and sent them off to be printed the same size.

Then you can see the point at which increases in resolution become wasteful.  Then you know how many pixels = how many mm of good printing.  You want to avoid, as far as possible, wasting time on huge renders.  So the best thing to do is determine how many pixels x pixels your images need to be to print nicely.

I know this sounds like a faff.  But what I have found is that generally the printers either a - don’t get it because they are not used to dealing with digital information or b - won’t commit.

So how can I handle this when I don’t know who the printer will be, let alone what equipment they have or the talent they have running their equipment?

The solution I have found to work most of the time is to give them a file they are used to working with. I change the file in Photoshop to whatever they want. So what I need is to be able to convert my Bryce file into something Photoshop can read, i.e. tiff, jpg, png or psd, so I can walk into a printer in, say the Philippines, hand him a thumb drive and say print this on metallic paper at 11x14 inches. This will most certainly mean stuffing in more data than is critical in the initial file.

Can Bryce render a tiff, jpg, png or psd , outside of render to disc, which we agree is not prime time?

Hold the presses!

I figured out the pixel size by taking something I have had printed in to Photoshop and letting it calculate the pixel size.

It is 8333x5556 pixels.

Will that work?

vindazi - 18 September 2012 12:29 PM

So how can I handle this when I don’t know who the printer will be, let alone what equipment they have or the talent they have running their equipment?

The solution I have found to work most of the time is to give them a file they are used to working with. I change the file in Photoshop to whatever they want. So what I need is to be able to convert my Bryce file into something Photoshop can read, i.e. tiff, jpg, png or psd, so I can walk into a printer in, say the Philippines, hand him a thumb drive and say print this on metallic paper at 11x14 inches. This will most certainly mean stuffing in more data than is critical in the initial file.

Can Bryce render a tiff, jpg, png or psd , outside of render to disc, which we agree is not prime time?

A series of small tests to determine the best resolution for yourself.

Here are potential output formats.  Straight after the render is complete.

File > Export image.

vindazi - 18 September 2012 12:39 PM

Hold the presses!

I figured out the pixel size by taking something I have had printed in to Photoshop and letting it calculate the pixel size.

It is 8333x5556 pixels.

Will that work?

Sounds excessive to me.  Bit then it is your render time.  What is the viewing distance for these images?

vindazi - 18 September 2012 12:29 PM

So how can I handle this when I don’t know who the printer will be, let alone what equipment they have or the talent they have running their equipment?

The solution I have found to work most of the time is to give them a file they are used to working with. I change the file in Photoshop to whatever they want. So what I need is to be able to convert my Bryce file into something Photoshop can read, i.e. tiff, jpg, png or psd, so I can walk into a printer in, say the Philippines, hand him a thumb drive and say print this on metallic paper at 11x14 inches. This will most certainly mean stuffing in more data than is critical in the initial file.

Can Bryce render a tiff, jpg, png or psd , outside of render to disc, which we agree is not prime time?

I would say take jpg out of the equation since the compression can deminish the details you’re trying to bring out with the high resolution. Bryce can do bmp or tiff, I’m not sure about tiff but I think it’s the same as bmp in that they both preserve the picture quality better then jpg. If need be the bmp or tiff can be converted in photoshop to .png which also is good at maintaining picture quality. Bryce can also save an image as a psd but I’m not sure how psd files are at perserving picture quality?

LordHardDriven - 18 September 2012 12:44 PM

vindazi - 18 September 2012 12:29 PM

So how can I handle this when I don’t know who the printer will be, let alone what equipment they have or the talent they have running their equipment?

The solution I have found to work most of the time is to give them a file they are used to working with. I change the file in Photoshop to whatever they want. So what I need is to be able to convert my Bryce file into something Photoshop can read, i.e. tiff, jpg, png or psd, so I can walk into a printer in, say the Philippines, hand him a thumb drive and say print this on metallic paper at 11x14 inches. This will most certainly mean stuffing in more data than is critical in the initial file.

Can Bryce render a tiff, jpg, png or psd , outside of render to disc, which we agree is not prime time?

I would say take jpg out of the equation since the compression can deminish the details you’re trying to bring out with the high resolution. Bryce can do bmp or tiff, I’m not sure about tiff but I think it’s the same as bmp in that they both preserve the picture quality better then jpg. If need be the bmp or tiff can be converted in photoshop to .png which also is good at maintaining picture quality. Bryce can also save an image as a psd but I’m not sure how psd files are at perserving picture quality?

I usually go with .png because .psd and .tiff files tend to being fatter without being phatter. But it is difficult, and perhaps ill advised, to standardize with my low level of knowledge. I can convert in Photoshop from tiff. psd or png to what ever I need. David. pick the one you think best. I threw in the jpg because many labs require sJPG files.

My work is typically viewed at about 2-3 feet for hanging images.

vindazi - 18 September 2012 11:35 AM

I want to do 18x12 at 200 dpi.

I assume 18x12 are inches and you want them for 200 dpi. Set the document size in Bryce to 3600 x 2400, this is 18 x 200 = 3600 and 12 x 200 = 2400. This is the information you must send to that printer to get a 18 x 12 inch picture with a quality of 200 dots per inch.

For prints on photo paper (I have been doing this regularly for the last 8 years or so), 140 to 160 lines per inch gives the best quality. Photo paper is chemical and the photo guys talk about lines per inch, not dots or pixels per inch. Nevertheless, you can take it as pixels per inch (ppi).

I once made renders using a modified test image (see below) on a 2D Face. These renders, I sent in to a photo printer shop for 5.9 x 4.3 inch photo prints. I rendered at different document sizes at 72 dpi.

Doc size: 640 x 480 = 112 lines per inch, result quite good.
Doc size: 800 x 600 = 140 lines per inch, excellent.
Doc size: 1024 x 768 = 179 lines per inch, not so good.
Doc size: 1280 x 1024 = 236 lines per inch, crap.

Using a laser or ink jet printer is a bit different. I highly recommend to make a reference render and have it tested with several document sizes for the same resulting size. We can theoretisize a lot but the quality of a print also depends on the printing machine. The result on your home printer may look better or worse than what you get from the professional printer.

It doesn’t matter if the picture used has 72, 96, 200, 300 or whatever dpi’s set in the file. All you need is to tell what size the result should be.

In the 1990s, we worked with CCD astro cameras that cost $10,000 and had 192 x 165 pixels (imagine!) and those tiny photographs were printed in a magazin at half page size - and 8 x 6.8 inches on a home printer and they look good.

That is why I say invest a bit of money and do some testing. You only have to do it once. Then you know what document size you have to set to get your renders as hardcopy in a quality you or your customer expects.

And here is yet another tutorial to render wider than 4000 pixels: http://www.horo.ch/raytracing/tuts/online/tut21/minitut21_en.html Be aware that the width is limited to 4000 pixels, not the height. You can render a portrait 4000 x 5333 pixels directly on the screen.

Thanks everyone for you help with this.

While I was trying your suggestions and pondering how to best utilize them, I stumbled on what might be another approach. Maybe it was what you were trying to tell me but I wan’t getting.

I had the test image set at a standard 640x480 aspect ration. In the document setup I set the anti-aliasing to superfine and jacked up the render resolution to 2560X1920. Then I rendered it at superfine in the Quality drop down. ThenI could export the image or Save the image as a jpeg, tiff, psd, or png, depending on which option I chose.

I have only seen these images on my screen but the image size in Photoshop is relatively large. I will have to send some test prints out to see the results.

I am a bit suspect of this approach because it was too easy. What could I be missing?

Bryce IS easy - and fun besides.

vindazi - 18 September 2012 02:04 PM

Thanks everyone for you help with this.

While I was trying your suggestions and pondering how to best utilize them, I stumbled on what might be another approach. Maybe it was what you were trying to tell me but I wan’t getting.

I had the test image set at a standard 640x480 aspect ration. In the document setup I set the anti-aliasing to superfine and jacked up the render resolution to 2560X1920. Then I rendered it at superfine in the Quality drop down. ThenI could export the image or Save the image as a jpeg, tiff, psd, or png, depending on which option I chose.

I have only seen these images on my screen but the image size in Photoshop is relatively large. I will have to send some test prints out to see the results.

I am a bit suspect of this approach because it was too easy. What could I be missing?

The superfine quality is to do with render quality it will not affect the number of pixels.

Document settings will allow you to change aspect ratio, document resolution and render resolution up to a maximum width of 4000 pixels.  So long as you save your final render in a non-compressed format.  Like bmp you can use your paint package to change it later, compress it and also, print it out at any size you desire.  The print size should not affect the image resolution you have already determined in pixels x pixels.