why are photos automatically going to 300dpi

[LunchboX3904]

I've been shooting a ton with my new D50 and I love it, but when I put a photo into PS, it automatically says its in 300dpi. it didn't do this for the first 50 shots i put in there. is it PS or my camera? thanks!

 

[Ice Czar]

dpi?

your camera likely has several resolution settings, depending on what you have selected will determine the number of pictures you can save to the camera's memory

when opening a picture in photoshop that native resolution will be where you start from
but generally its not dots per inch (dpi), rather pixels

 

[Tiny]

it shows both, pixels and dpi, when you resize it in Photoshop. I know my camera takes them at 2300something x 1800something, or something, and it shows it at 300dpi when the resize dialog box pops up. But I just have a 6.2 MP camera.

 

[EGGO]

Out of curiosity, what type of camera do you have?

Perhaps by knowing the make and model, we can see if it does have such a setting (which is nice, I don't know if my Rebel XT can do that). That would really narrow it down to the one choice.

 

[synergyo1]

The guy says he has a Nikon D50, which is a DSLR.

 

[Osiris]

Isn't the dpi something photoshop applies so that pics can be printed?

It doesn't affect the actual digital image at all as far as I know.

 

[meatycheesyboy]

What are you using the photos for? If you're only going to be viewing them on a monitor, tv, etc. then you can disregard the DPI. It will not affect how it displays on screen or the file size whether it be 300, 3, or 3,000,000,000. For on screen viewing the only thing that matters is the actual pixel dimension

For example, a 1024x768 at 1 DPI will display the same as a 1024x768 at 300 DPI on a monitor and it'll be the same file size (talking about bytes here not dimensions).

If you're going to be printing the photos then the DPI matters and you've opened a whole new can of worms.

 

[LunchboX3904]

i understand what dpi is for the most part, but it does affect the image on a screen. text is enlarged. that's why it's annoying. I put my own little watermark in the corner of my pictures and they're huge at even 10pt font. I suppose I don't really need to put that there, but I would like to know how to open photos at 72 dpi, instead of having to resize it that way.

 

[meatycheesyboy]

Sorry, I didn't realize that you were adding type to the images. You are correct, DPI does affect type measurement.

If you use 36pt type on a 300 DPI image then convert it to a 100 DPI image, you're type will magically become 108pt type.

Also, if you want you're type pont sizes to match what you see in other apps (apps that don't recognize things like DPI like word or powerpoint, etc.) then you'd want your image to be 96 DPI, not 72 since 96 is what most computer monitors are at.

As for why your images are coming in at 300 DPI from your camera instead of 72, I don't know, its probably a settng on the camera but I've neer used the camera before. But in your image editing/processing program (Photoshop, Paint Shop Pro, etc.) you shouldn't be a hard process to just convert it to 72 while keeping the same pixel dimensions. If you need to know how to do it in Photoshop, I can walk you through it.

Sorry for the long post of things you probably already know, just trying to cover some bases since DPI is a topic that confuses many many people. Also, sorry I couldn't help you more with your specific problem.

*edit* One last thing, you can have photoshop display text sizes in pixels instead of points then it'll be DPI independent and will no longer change if you convert an image from say 300 DPI to 72 DPI. I'm sure other programs can do it as well but if you need to know where to find the setting in photoshop, just tell. *edit

 

[LunchboX3904]

thanks for all the info. I do know how to retain the pixel dimensions and reduce the dpi, it's just kind of a hassle for EVERY single picture. I guess I'll just live with it until I find what it is. didn't used to do it, so i know it's a setting of some sort.

 

[Ice Czar]

some background on dpi

dots per inch refered to screen counts once apon a time, you would actually lay what amounted to a photographic window screen over film and then take an exposure
each opening in the screen acting like an apeture in a film camera, so depending on the exposure and what it was reflecting off of and through the lens more or less light would come through. The film itself had no greyscale and thus youd end up with black and white only

suitible to being either a raised or lowered portion of a printing plate that ink would adhere to and be physically transfered to paper (lithography)

the number of "wires" per inch being the screen count or conversly the number of dots being the dpi.

then came the digital age

Dots per Inch is a measurement used both on monitors and printers. The measurements are done different ways though. The higher numbers on printers generally represent more detailed print quality (i.e. 1440x1440 would be very high resolution printing). The lower numbers on monitors represent clearer picture quality (i.e. .22 dpi would be a very high quality monitor).

and also operating systems


how photoshop defines dpi

In order to produce high-quality images, it is important to understand how the pixel data of images is measured and displayed.

Pixel dimensions

The number of pixels along the height and width of a bitmap image. The display size of an image on-screen is determined by the pixel dimensions of the image plus the size and setting of the monitor.

For example, a 15-inch monitor typically displays 800 pixels horizontally and 600 vertically. An image with dimensions of 800 pixels by 600 pixels would fill this small screen. On a larger monitor with an 800-by-600-pixel setting, the same image (with 800-by-600-pixel dimensions) would still fill the screen, but each pixel would appear larger. Changing the setting of this larger monitor to 1024-by-768 pixels would display the image at a smaller size, occupying only part of the screen.

When preparing an image for online display (for example, a Web page that will be viewed on a variety of monitors), pixel dimensions become especially important. Because your image may be viewed on a 15-inch monitor, you may want to limit the size of your image to 800-by-600 pixels to allow room for the Web browser window controls.

Example of an image displayed on monitors of various sizes and resolutions

Image resolution

The number of pixels displayed per unit of printed length in an image, usually measured in pixels per inch (ppi). In Photoshop, you can change the resolution of an image; in ImageReady, the resolution of an image is always 72 ppi. This is because the ImageReady application is tailored to creating images for online media, not print media.

In Photoshop, image resolution and pixel dimensions are interdependent. The amount of detail in an image depends on its pixel dimensions, while the image resolution controls how much space the pixels are printed over. For example, you can modify an image's resolution without changing the actual pixel data in the image--all you change is the printed size of the image. However, if you want to maintain the same output dimensions, changing the image's resolution requires a change in the total number of pixels.

Example of an image at 72-ppi and 300-ppi

When printed, an image with a high resolution contains more, and therefore smaller, pixels than an image with a low resolution. For example, a 1-by-1-inch image with a resolution of 72 ppi contains a total of 5184 pixels (72 pixels wide x 72 pixels high = 5184). The same 1-by-1-inch image with a resolution of 300 ppi contains a total of 90,000 pixels. Higher-resolution images usually reproduce more detail and subtler color transitions than lower-resolution images. However, increasing the resolution of a low-resolution image only spreads the original pixel information across a greater number of pixels; it rarely improves image quality.

Using too low a resolution for a printed image results in pixelation--output with large, coarse-looking pixels. Using too high a resolution (pixels smaller than the output device can produce) increases the file size and slows the printing of the image; furthermore, the device will be unable to reproduce the extra detail provided by the higher resolution image.

Monitor resolution

The number of pixels or dots displayed per unit of length on the monitor, usually measured in dots per inch (dpi). Monitor resolution depends on the size of the monitor plus its pixel setting. Most new monitors have a resolution of about 96 dpi, while older Mac OS monitors have a resolution of 72 dpi.

Understanding monitor resolution helps explain why the display size of an image on-screen often differs from its printed size. Image pixels are translated directly into monitor pixels. This means that when the image resolution is higher than the monitor resolution, the image appears larger on-screen than its specified print dimensions. For example, when you display a 1-by-1 inch, 144-ppi image on a 72-dpi monitor, it appears in a 2-by-2 inch area on-screen. Because the monitor can display only 72 pixels per inch, it needs 2 inches to display the 144 pixels that make up one edge of the image.

Printer resolution

The number of ink dots per inch (dpi) produced by all laser printers, including imagesetters. Most desktop laser printers have a resolution of 600 dpi, and imagesetters have a resolution of 1200 dpi or higher. To determine the appropriate resolution for your image when printing to any laser printer, but especially to imagesetters, see "screen frequency."

Ink jet printers produce a microscopic spray of ink, not actual dots; however, most ink jet printers have an approximate resolution of 300 to 720 dpi. To determine your printer's optimal resolution, check your printer documentation.

Screen frequency

The number of printer dots or halftone cells per inch used to print grayscale images or color separations. Also known as screen ruling or line screen, screen frequency is measured in lines per inch (lpi)--or lines of cells per inch in a halftone screen.

The relationship between image resolution and screen frequency determines the quality of detail in the printed image. To produce a halftone image of the highest quality, you generally use an image resolution that is from 1.5 to at most 2 times the screen frequency. But with some images and output devices, a lower resolution can produce good results. To determine your printer's screen frequency, check your printer documentation or consult your service provider.

Note: Some imagesetters and 600-dpi laser printers use screening technologies other than halftoning. If you are printing an image on a nonhalftone printer, consult your service provider or your printer documentation for the recommended image resolutions.

Screen frequency examples: A. 65 lpi: Coarse screen typically used to print newsletters and grocery coupons B. 85 lpi: Average screen typically used to print newspapers C. 133 lpi: High-quality screen typically used to print four-color magazines D. 177 lpi: Very fine screen typically used for annual reports and images in art books

File size

The digital size of an image, measured in kilobytes (K), megabytes (MB), or gigabytes (GB). File size is proportional to the pixel dimensions of the image. Images with more pixels may produce more detail at a given printed size, but they require more disk space to store and may be slower to edit and print. For instance, a 1-by-1-inch, 200-ppi image contains four times as many pixels as a 1-by-1-inch, 100-ppi image and so has four times the file size. Image resolution thus becomes a compromise between image quality (capturing all the data you need) and file size.

Another factor that affects file size is file format--due to varying compression methods used by GIF, JPEG, and PNG file formats, file sizes can vary considerably for the same pixel dimensions. Similarly, color bit-depth and the number of layers and channels in an image affect file size.

Photoshop supports a maximum file size of 2 GB and maximum pixel dimensions of 30,000 by 30,000 pixels per image. This restriction places limits on the print size and resolution available to an image.

 

[Ice Czar]

as far as OS's define dpi

Macs are 72dpi, Windows are 96dpi

Apple's 72 dpi logical inch was close to accurate text size on the early Macintosh screen (1984), which is why Apple selected the 72 dpi number back then. Apple still uses that number today for text logical inches, but that number was only about the size of THAT screen. That 1984 Macintosh graphical screen was something new, it could show various font faces and sizes, italics and bold, even proportional fonts on the screen for the first time. We take this for granted today, but graphic text on the video screen was a new idea then. MS-DOS screens did not show graphic text, and instead used screens dimensioned as 80x25 fixed-width characters of one bit-mapped font.

And back then, Apple did brag about 72 dpi and about WYSIWYG (What You See Is What You Get), meaning text on that screen looked the same, and matched the size of the same text printed on paper. The size accuracy was not because of the number 72 dpi per se, it was because this logical inch size was selected to match this physical screen size. We don't hear about WYSIWYG today - it is not possible now because modern screens vary in size.

Microsoft later used 96 dpi logical inches in Windows to intentionally show larger screen text for better readability

meaning that unless for some odd reason you working with an antique monitor 72dpi, or 96dpi has no bearing whatsoever on what your now doing

here is a nice diatribe about dpi and scanning
Say No to 72 dpi

Each of the three images below are 412x324 pixels in size, which is why the video system shows each of them as 412x324 pixels size on the screen.

To make the point that the image resolution dpi number (the scaled printing resolution stored in the image file) simply does not matter on the screen, these three images below are now scaled individually to 7 dpi, 72 dpi, and 720 dpi. If you print them (using a photo editor), they are now three very different images in that regard. These image files actually do individually contain these three different dpi numbers, which is instruction to the printer how to print them (how to space the pixels on paper, how large to print the image on paper).

412 x 324 pixels, 7 dpi, prints 58 x 46 inches

412 x 324 pixels, 72 dpi, prints 5.7 x 4.5 inches

412 x 324 pixels, 720 dpi, prints 0.57 x 0.45 inches


Frankly, I don't see much difference on the screen. <grin> (and this is YOUR video system that we are using too). I am not making this up, you can see what in fact actually happens, and it's going to be real hard to dispute that. But for anyone who still wants to argue that there is any significance of 72 dpi (or 96 dpi) on the screen, please begin by explaining why there is no evidence whatsoever of it on the screen. If 72 dpi matters at all, then how can these three very different images appear identical? Please also explain how any 72 dpi notion might have been used to create these 412x324 pixel images from small 35 mm film (film size is 36x24 mm, about 1.4 x 0.92 inches).

I am teasing - I know it is not possible that anyone can explain how 72 dpi is important in any way to these (or any) screen images. The notion of 72 dpi is flat wrong - video simply doesn't work that way. There is no concept of dpi on the video screen. It should instead be very clear from the above example that images are obviously shown on any screen only according to their size in pixels. In every case, you should just create the image size (pixels) that is the size that you want to see (pixels). So, forget about 72 dpi, it does not work that way. 72 dpi is a false notion, even worse than useless, because it is counter-productive, both to results and to understanding how it really works. There is no concept of dpi in the video system. There are only pixels.

there is quite a bit more which I think you should read

to actually answer your question
Im not sure, since how the watermark is being applied is something Im unfamiliar with
Ive generally limited myself to combined type and pictures in Photoshop itself
where I would start with the native resolution enlarge or reduce the image size
then apply a new type level which would then refer to the size of the image to determine it porportional size in points

in Postscript 72 points equals one inch
that doesnt mean 72 points would have a Cap hieght of one inch , that differs from font to font see below

sometime the ascender height is higher than the Cap height, in which case the type appears even smaller for a given point size and a low x height can compound that in comparision to a Cap height, an extreme example being Bernhard Modern

thus the apperant size of various typefaces all at the same point size can be substantially different

 

[Ice Czar]

and just to confuse the issue some more

http://web.archive.org/web/20021207143047/http://www.proview.net/dotpitch.htm

how monitors (and different types of CRT monitors) define dpi
which is more accurately defined as dot pitch

CRT monitors again employing screens be they apeture grill or shadowmask

with a triangle of a red green and blue dot equaling a pixel

sorry the site is gone and there are no pictures saved at the archive

Some dot-pitch basics first: Monitors create colors with red, green, and blue phosphors. By lighting them up in different intensities, the display creates the illusion of other colors. In the vast majority of tubes, these colored phosphors repeat in patterns, with alternating rows offset from each other. Dot pitch is the distance, center to center, between the two closest dots of the same color; each set of three of the closest red, green, and blue dots is called a triad. Notice that a given dot lies halfway between dots of the two other colors in the row below. Each dot also lies directly above the same color dot two rows below.

In most CRTs, the vertical dot pitch – the vertical distance between the centers of two same-colored dots – matches the diagonal dot pitch, which is the distance between either dot and the closest same-colored dot on the row between the two. Draw lines between the three dots, and you get an equilateral triangle.

The Hitachi CRT arranges the phosphors slightly differently. Here, if you draw lines between the three closest dots of a given color, you don't get an equilateral triangle. You get an isosceles triangle, with two equal-length diagonal sides – 0.26mm in this case – and a slightly longer vertical side. For lack of a better term, we refer to this as an asymmetrical arrangement.

So in an asymmetrical arrangement, the diagonal dot pitch becomes the closest distance between two dots of the same color. But using that as the dot-pitch spec presents a problem, because a 0.26mm diagonal dot pitch in an asymmetrical arrangement is not equivalent to a 0.26mm dot pitch in a standard CRT.

You can see the difference by examining the horizontal component of the diagonal pitch (the horizontal dot pitch), which turns out to be a useful measurement. When you divide this pitch into the image width, you get the maximum number of triads that fit across the screen--which is also the maximum theoretical resolution the CRT can handle, assuming the monitor electronics are up to it.

For a standard CRT, the horizontal dot pitch equals 0.866 times the diagonal pitch, which comes to 0.2252mm horizontal measurement for a 0.26mm diagonal pitch; this calculation is derived from the geometric properties of equilateral triangles. But for an asymmetrical arrangement, with its isosceles-based geometry, the calculation depends on both the vertical and diagonal pitch of the particular CRT. That means you either need more information to perform the calculation, or you need someone to provide the data.

The Hitachi CRT's horizontal dot pitch happens to be 0.22mm. This turns out to match the horizontal dot pitch of a standard CRT with a 0.254mm diagonal dot pitch. Most of the manufacturers who use the Hitachi CRT quote the horizontal dot pitch value of 0.22mm. However, several – including Optiquest®, Princeton, and Sampo® --specify the diagonal dot pitch instead.p

I wont get into how LCDs translate dpi resolution comparisions

 

[LunchboX3904]

wow dude. ummm, i just wanna know how to make my pics open up in photoshop at 72 dpi. that's it. thanks for all the info, but quite unnecessary.

 

[Ice Czar]

but quite unnecessary.

especially when you dont read it

wow dude. ummm, i just wanna know how to make my pics open up in photoshop at 72 dpi.

72dpi is a mac standard regarding the size of the graphics appearing on your monitor screen
if its a apple monitor circa 1984


you need to refer to the documentation of whatever it is (the camera?) that placed the digital watermark on the photos

 

[LunchboX3904]

72dpi is a mac standard regarding the size of the graphics appearing on your monitor screen
if its a apple monitor circa 1984


you need to refer to the documentation of whatever it is (the camera?) that placed the digital watermark on the photos

I looked through the manual for the camera but I didn't se anything on it. I remember reading about a print setting somewhere but forgot about it. The reason for 72 dpi, is because that's just what I have always worked at in photoshop and the fonts did what they were supposed to, so no need to change. well, I really appreciate all your help.....you win some, you lose some.

P.S. It's a Nikon D50 digital SLR camera.

 

[MixManSC]

I do not believe you can change it. We use several digicams in my shop and any of the jpg shots we open in photoshop open at 300dpi. The only time we get something different is when we shoot in RAW mode in which case raw files present a different open dialog where you have a ton more options to choose prior to opening the actual photo such as exposure, incresing resolution, etc. I do believe though that the number assigned to the DPI on digital camera pics is set in the cameras firmware and is generally changed in the camera's "quality" setting. They generally do not shop the DPI though it will usually simply say "standard, fine, etc.) but on the Minolta 7Hi I just tried it on when I set it to it's lowest quality then the jpg pics open as 72dpi, we always keep it set on it's highest jpg resolution though which always opens at 300dpi or we shoot in RAW mode. Then you also usually have another setting for resolution such as 1280x1024, 1600x1200, etc. to choose from. Do keep in mind though - if you set your camera to shoot in it's low qaulity mode then the only place those shots will ever look good is on a monitor as their print size will be limited to a inch or so a high if you try to increase them to 300dpi for printing. Aside from that though you can generally get away with printing at about 150 to 200dpi with excellent results as your printers dpi or resolution is not at all the same thing or meaning as your pictures dpi which is a whole different long explanation which is covered above. To print very large though the higher the pictures dpi and resolution the better. We bring in 5mp RAW images at 600dpi and 4000 or so resolution, drop the dpi to 150 and can print the images at 48" across with excellent quality.

 

[LunchboX3904]

thanks man. that's what I wanted to hear. I've shooting at Large size, with Fine quality. So I guess that's really only necessary when using stuff for photos for print. I generally only use my photos for online stuff like DA. I would like to print stuff though eventually so I might just tolerate making the adjustments in photoshop to get it into 72 dpi. thanks for the explinations. I'll come back to you guys if I need help printing later on.

 

[drakken]

If you need to resize anything or edit the photos dpi does matter as it dictates how fine a detail you can work in. ie small pik with big pixels would be low dpi like 72, resizes like shit, big pik with very small pixels like say 700 dpi resizes with virtually no lose in quality.