Hot answers tagged dpi
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Generating High Quality Ink Jet Prints
Making effective use of professional photographic ink jet printers is tricky business, especially when the statistics that are commonly used to describe these printers are vague and misleading. Learning how a ink jet printers function, how to properly interpret their capabilities, and make the most effective use of ...
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There are some general rules you can use to determine the "maximum" (I use that term loosely) print size. Keep in mind that the quality of a print is often more dependent on what is being printed than its size in megapixels, and even if your image size is not dense enough to mathematically fit onto a certain page size, you can still blow most images up ...
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Emprical Study: Extreme digital upscaling
For all of the theory above, thats all it currently is...theory. It is the end result of days of research on the physical characteristics of printers, the theory behind printing and ink, the concepts of DPI and PPI, etc. The real question is, how does it stack up against empirical evidence? Does it withstand the ...
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The straightforward answer to your question is very simple arithmetic: 32×300 = 9600 and 18×300 = 5400, so 32 inches by 18 inches at 300 dots per inch is 9600 by 5400.
However, it gets a little more complicated when you consider a more complicated relationship between pixels and colored dots in your output medium. For details on this, take a look at ...
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The values are arbitrary and meaningless, and only serve to confuse people. The EXIF standard seems to imply that if the tag is missing, 72 is the (still-meaningless) default. However, it is apparently mandatory for the TIFF standard, from which the JPEG/EXIF format basically inherits everything. So maybe it has to have some value to properly comply with the ...
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When it comes to print, terms like DPI, resolution, PPI, etc. get thrown around without much care or concern as to what they truly mean. So, before I send you off to a more in-depth answer about DPI, PPI, resolution, and print, a quick summary:
DPI: Dots Per Inch
A 'dot' is a single element of a pixel
On a computer screen, a dot is a single 'sub-pixel' ...
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DPI, or Dots Per Inch relates to the dot density when printing.
To help better understand the relationship of DPI to pixel dimensions, take an 800x600 pixel image for example:
Using 300dpi, an 800x600 image will print 2.6x2 inches.
Using 200dpi, an 800x600 image will print 4x3 inches.
Using 100dpi, an 800x600 image will print at 8x6 inches.
Notes:
As ...
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Generating High Quality Ink Jet Prints: Summary
Making effective use of professional photographic ink jet printers is tricky business, especially when the statistics that are commonly used to describe these printers are vague and misleading. Learning how a ink jet printers function, how to properly interpret their capabilities, and make the most effective ...
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The information above is quite good, so I won't try to compete, but here is a nice infographic:
The boxes are the number of megapixels for a print of the size in inches according to the scales on the axes. This is at 300ppi, which is a standard for the print resolution of many images.
This great graphic comes from an article at D215.
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Emprical Study: Does PPI Really Matter?
For all of the theory above, thats all it currently is...theory. It is the end result of days of research on the physical characteristics of printers, the theory behind printing and ink, the concepts of DPI and PPI, etc. The real question is, how does it stack up against empirical evidence? Does it withstand the test ...
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DPI stands for Dots Per Inch.
It's used to descibe the output resolution of printers, and it's also often used instead of the PPI (Pixels Per Inch) unit, which is more appropriate for describing the resolution of computer screens, scanners and image files.
So, a printer might have a resolution of 2400 DPI, but that doesn't mean that you can print an image ...
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jrista has the start of the formula, and it covers images viewed at arm's length quite well. But that 'conventional wisdom' devolves into unreasonable numbers as soon as you get to anything "big", say even a 16x20... requiring 5-6000 px. And if you hit poster size, say 30x40... 9000x12000... 108 MPix?!
When you're talking about really big prints, it's ...
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JPEG Quality of 9 ~ 10 out of 12 (or 70 ~ 84 out of 100) is pretty indistinguishable from uncompressed. See this article for an in-depth comparison. In short, if you have less color gradients, you can get away with higher compression (lower quality values).
For PPI (what you care about), in general, 240 to 360 PPI is high quality. This depends on typical ...
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It depends on a few factors - primarily the print technology that is going to be used, and secondly what the print is to be used for.
The D700 shoots at 4256 × 2832 (12.1 MP), so the largest Square frame you can print at 1:1 pixel ratio would be 2832 x 2832 pixels.
Lets say the print is to be at 600 DPI, which is a fairly standard high quality signage dpi, ...
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Pixels per inch don't actually exist until the image is rendered onto some physical medium such as paper or the monitor on your computer. The device doing the rendering determines PPI and PPI determines how large the image will appear when rendered.
Rendering your 4000x3000 on a device capable of producing 240 PPI would produce a 16.6"x12.5" physical ...
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PNG compression quality varies greatly from compressor to compressor. The standard PNG compression in Photoshop for example can sometimes commonly be beat by large percentage points. This is primarily due to more intelligent switching algorithms when it picks the kind of prediction to do for a certain set of pixels. Most of the "additional" compression is ...
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The number is just a random filler. It has no significance since the camera does not know how big you will print.
Most cameras default to 72 which according to the EXIF standard is the default value. Some cameras let you set it yourself. Then again, it has little meaning unless you will print all your images without cropping exactly at the same size.
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The DPI setting coming out of the camera doesn't mean much (if anything). You have a fixed number of pixels coming out of the camera (4272 x 2848, to be exact). Since you're enlarging it quite a bit, you probably want to shoot in raw format to ensure you get everything that camera can produce.
Once you've done that, you might want to "upres" the picture to ...
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The DPI setting (or PPI to be pedantic) only specifies how the pixels should be translated into absolute metrics.
The 5400 PPI for the 900x500 pixel image only means that it represents 0.1667x0.0926 inches (4.23x2.35 mm) in absolute metrics.
When an image is shown in the browser, it totally ignores the absolute metrics. The image is shown by its pixel ...
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An image has no physical size, it is simply a collection of pixels. A 1280 pixel wide image will be rendered 20cm wide on my old computer monitor, but the same image will be rendered just 9cm wide on my phone.
The DPI value embedded is metadata recording the "intended" physical size. As such it can be set to whatever value the user desires. The value is ...
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The DPI reported in a JPEG file is just a metadata field. That is, it's intended to offer a hint to software that displays or prints image files, but it's not immutable, in practice it's not authoritative or enforced, and it's usually ignored by most software and photographers alike. The actual DPI of a displayed image is determined by the absolute ...
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Besides the algorithms described in other answers, small images' file sizes can be reduced by stripping out metadata from the file. EXIF/IPTC data can add up to 64 kilobytes to a JPEG image.
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What you're suggesting in terms of resizing sounds correct, and you can use any number of tools to do it. If you're on Windows you can use IrfanView, and naturally almost any of the pro line of tools will do it (such as Photoshop).
It's also worth noting that most of these tools will also let you set the width as a function of their physical size (cm, ...
2
Your confusion is understandable because the DPI in the photo is meaningless. It does not make any sense to speak about DPI without something that can be measured (like a print) but the cameras have to put something in there, so most put 72 and a few ones let you specify a different value.
To get the DPI of something divide the number of pixels by the size ...
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Firstly, DPI really isn't a unit of resolution, but one of dot density. For example, you can have a 300x300 pixel image and print it at 300dpi for a 1 inch x 1 inch print, or you can print it out at 100dpi for 3 inch x 3 inch output. In both of these cases, the image's resolution (300x300 pixels) remains the same.
As for compression:
The most common ...
2
PPI (pixels per inch) value of a digital image is only metadata used to determine how large an image should be printed.
You can set the value to be whatever you like, without having to resize or do anything with the actual pixels.
For example if you took your 4000 x 3000 image at 240PPI and placed it into Adobe InDesign it would end up 16.6 x 12.5 inches ...
2
Scanning at max resolutions is always the best bet for quality but worst for speed and file size. Try to preview the image, crop and the scan with de-smear or anti-alias option if avail.
If image is magazine quality, chances are it was printed in 1200 to
2400 dpi. WHen scanning any dot pixel image near the same resolution
is prone to aliasing ...
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You are confused because dots on an image do not correspond to dots on a printer.
The recommended 300 DPI is for images where each dot is actually a pixel and can be of any number of colors, 16 millions for a JPEG, more for other formats.
A printer requires many dots to render a single image pixel, sometimes over 100. That is because a printer has between ...
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You simply need to set a low enough resolution. Set the image size no larger than the number of pixels to be displayed in the browser. Screen resolutions are generally lower than print, but it's still going to look "ok" printed by most people's definition even though it will clearly not be professional quality.
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To put some rule-of-thumb numbers to it: a print resolution of about 300dpi is required for a high-quality print, but for non-picky print many people will be fine with 100dpi. Below that, even non-skilled viewers will probably object.
So, in order to reduce the image below what might make a great print at 5x7, 1500x2100 pixels is the threshold. That's more ...
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