Changing image dpi

I have several hundred images at various dpi and I'd like to convert them all to 300 dpi. I can change the resolution manually with Preview or Photoshop CS5 and it's also easy to change all the image sizes with Automator, but I can't figure out how to automate a dpi conversion. Anyone have any suggestions?

Obviously the value is stored within the file, but it is stored as meta data. As such, you shouldn't need to alter the image data in order to change it.
Yes, but that's not the way any software I've ever seen saves an image. They all rewrite the entire record of data, regardless of whether the image pixels have changed or not.
Not the answer you want to hear, but the answer is no, you can't change the resolution without affecting the image. At least not when using a lossy image format. Could they, should they save an unchanged JPEG by simply copying the image data tag from the old file to the new one instead of recompressing the uncompressed image data you're working from in RAM? Yes, it should be easy to do, but no software does that.
I took a handful of test TIFF images and saved them as TIFF with LZW compression; TIFF with ZIP compression; and JPEG at the highest quality level (noted as 12 in Photoshop), baseline Standard. Note that LZW and ZIP compression in TIFF is lossless. Image quality never changes.
All sizes in MB.
Uncompressed TIFF:
File 1: 52.7
File 2: 13.8
File 3: 10.4
File 4: 8.1
TIFF with LZW compression:
File 1: 17.7
File 2: 5.8
File 3: 5.6
File 4: 5
TIFF with ZIP compression:
File 1: 15.5
File 2: 5.1
File 3: 5.1
File 4: 4.6
JPEG level 12
File 1: 7.3
File 2: 2.8
File 3: 2.5
File 4: 2
Nod goes to JPEG of course for total space savings, but you're still losing image data, even on the first save.
TIFF with ZIP is slightly better than LZW, but takes a long time to save and open, and older software titles may not be able to open them.
TIFF with LZW saves almost instantly compared to ZIP (almost the same as uncompressed) and has been around forever. Pretty much any image editor can read it.

Similar Messages

Why is my image more pixelated after changing the DPI?

I am creating a magazine for a university project and I have chosen 2 images to be included in one of my articles. I changed the DPI of both images in PhotoShop to 300 DPI and saved them before placing them into my InDesign document but they appear to be even more pixelated after this than what they were when I placed them straight from the internet. Will they be like this when I print it or does it only look pixelated on my screen? Any help?

What is the effective resolution in InDesign? (look into the link panel.) (BTW resolution of an image is measured in PPI, not in DPI!)
Is the link up to date?
How do you proof it? Did you turn on the high quality display?
What file type are you using?
What is the scaling factor of the image in InDesign?
How did you change the resolution in Photoshop? What was the first resolution, did you change the size of the image?

How can i change the DPI of an image to 400 in illustrator?

I'm very stuck with trying to change the DPI of an image to 400 so that it is ready to print and the resolution will be fine once printed but i have no idea how to do this in illustrator?

dpi,
If you are talking about a raster image placed in Illy, you can only change the size to get the desired PPI/DPI.
If you are talking about raster effects or a raster image created in Illy, you may set the desired resolution of raster effects, or the desired resolution or total pixel x pixel size of the exported/saved image.
If you are talking about pure vector artwork, the resolution depends on your printer (driver) (settings), as Doug said.

How to change Tiff image DPI

Ho Guys,
I am looking for a code example to change Tiff Image DPI from 200 to 300.
Any suggestion is greatly appreciated.

You need to look for algorithms on scaling images. On such example is here:
http://www.rgagnon.com/javadetails/java-0243.html

IPhoto changes my dpi while editing - what to do?

Hello!
I have iPhoto 6 and have taken over 500 pictures for a wedding. Now they want to print bigger photos (A4) from my photos. All of a sudden we notice that all of the photos that I have taken with my Nikon D70, that are vertical have the dpi 70 instead of 300 needed for good quality print. Some of these pictures I have cropped but not all. I also have not turned all of them around. Most of them where taken the "right way" already with my camera. What I have done is that I have edited the colour or exposure in iPhoto. So why has iPhoto changed the dpi and why does it not ever notify me about this? Is there some way in how to prevent this from happening? Or change the dpi later in iPhoto? I can't possibly start re-editing each vertical photo in Photoshop, that is absurd! How can I prevent this from happening again?
Thank you for your help!

lkaranko:
Welcome to the Apple Discussions. The resolution has not been changed. It's the pixel dimension of the image that is the more important factor. If you take a 1600 x 1200 image at 72 dpi it will give you a 22" x 16.6" print. But if you take that same file and print at 300 dpi you'll get a 5.3 x 4" print.
iPhoto just reports the resolution at 72 dpi which, if printed at that resolution would give you a very large print. If you select a print size iPhoto will squeeze the available pixels into those dimensions. The smaller the print size the larger the resolution will be.
In rotating the files a new jpg file is created and when it's saved there will be some jpg compression applied. The original file is left intact and can be recovered by selecting the photo and using the Photo->Revert to Original menu option.
The bottom line is: as long as the number of pixels do not change (or by very much) the inherent resolution of the file is not changed.
Do you Twango?
TIP: For insurance against the iPhoto database corruption that many users have experienced I recommend making a backup copy of the Library6.iPhoto database file and keep it current. If problems crop up where iPhoto suddenly can't see any photos or thinks there are no photos in the library, replacing the working Library6.iPhoto file with the backup will often get the library back. By keeping it current I mean backup after each import and/or any serious editing or work on books, slideshows, calendars, cards, etc. That insures that if a problem pops up and you do need to replace the database file, you'll retain all those efforts. It doesn't take long to make the backup and it's good insurance.
I've written an Automator workflow application (requires Tiger), iPhoto dB File Backup, that will copy the selected Library6.iPhoto file from your iPhoto Library folder to the Pictures folder, replacing any previous version of it. You can download it at Toad's Cellar. Be sure to read the Read Me pdf file.

What is image dpi after "Reduce Image File Size"

Does anyone know the resulting image dpi after using the "Reduce Image File Size" command in pages? My mother is trying to prepare some things for pre-press, and can't send her document to the printing press, because the pages docs are friggin huge! I'm trying to give her the easiest option for resizing all of the many images in the document, but don't know if this is a viable option if the end product needs to be printed. I need the output to be at least 300dpi.

As fruhulda wrote, asking Pages to apply changes to the pictures isn't the good path.
In fact, it's a perfect way to get a fat file.
My practice is :
Prepare the document in Pages to define the wanted size of every embedded pictures.
Edit the picture files in a tool dedicated to this task so that the resulting files will be 300 dpis ones for the wanted sizes.
Then, replace the original pictures by the definitive ones.
In most cases, the file will be lighter than the original one and you will have the 300 dpis resolution (except if you apply shadows but it's an other story).
Yvan KOENIG (VALLAURIS, France) lundi 20 décembre 2010 19:36:56

How do you change the dpi on photos?

I am writing a book and inserting old photos into it.   These photos were scanned by people and sent by e-mail.   I need to change the dpi on the photos to 300 dpi for printing purposes.   I have just bought Lightroom, so I don't know a lot yet.   But, my first project is changing the dpi of these photos and inserting them into my book.   Thank you.

victoriafinland wrote:
I am writing a book and inserting old photos into it.   These photos were scanned by people and sent by e-mail.   I need to change the dpi on the photos to 300 dpi for printing purposes.
Actually, you don't need to change the resolution (which is PPI, not DPI), and anyway, you can't do this unnecessary thing in Lightroom. You do need to have enough pixels in the image to print at the desired size. So, for example, if the book calls for a 4x6 space to be filled with your photo, then you would need a photo that is 1200x1800 pixels (or larger). If your book requires the photos outside of Lightroom, then you would Export the photo (if necessary, enlarged) to the desired number of pixels, as in the example.
I have just bought Lightroom, so I don't know a lot yet.   But, my first project is changing the dpi of these photos and inserting them into my book.
So based on the fact that this is an unnecessary task, and that Lightroom won't do this anyway, your first project is now completed.

Two ways to change the DPI that are resulting in different outcomes... WHY?

I'm really having a hard time here, and I'm hoping someone can explain what I'm missing.
Because I like iPhoto's crop feature better then ACR or PS, I decided to add it to my process at the very end. Basically saving as a PSD, importing into iPhoto, cropping, and exporting the file back out in JPG or PSD format... The only catch is that iPhoto loves 72dpi, so I would have to add one more step to up the dpi using the Process Multiple Files feature in PSE6.
Problem - After I batch the files to 300dpi using the Process Multiple Files feature, everything went out of wack. For example, File 001.psd started out at 2848x4288, 33.7MB, and 240dpi. Once imported into iPhoto, cropped, and exported, the psd file was at 2458x3686, 25.1MB, and 72dpi. Then after the batch process the psd file is at 10242x15358, 310MB, and 300dpi.
Now if instead I take the 72dpi psd file and open it up in PSE6, go to image/resize/image resize, then change the Resolution number from 72 to 300 under Document Size, the file comes out to 2458x3686, 25.3MB, and 300dpi.
Are the two attempts to change the DPI not the same?
What am I missing here?
My goal is to end up with a 300dpi Max jpg image from the cropped files I exported from iPhoto, without them being way oversized. One would assume this is a straight forward process, no?
What am I missing?

Obviously, the two processes are not the same.
You didn't tell us what you did, what options you selected, in Process Multiple Files, so its hard to tell what you did wrong.
There's absolutely no reason to change the dpi, it is a meaningless number for screen display. The only time it matters is when you go to print, and since you didn't mention printing at all, I would recommend just forgetting this idea of batch changing dpi. It has no value whatsoever.

Change image to 2500 pixels on the longest side

I posted earlier but just found out how to change my dpi in an image from 300 to 72 dpi. (Can't find my earlier post.)
Now I'd like to, if possible,, In order to publish this is as a book cover on Kindle, change the number of pixels on the longest side of the image to the recommended 2500 Pixels.(Right now the image I'm interested in Is a bit more than that on the longest side.).

Go to image>resize>image resize. It would launch a image resize dialog.
From the bottom of the dialog, choose "Resample Image". in the drop-down below, you can choose the algorithm for resampling. Since you said the image you are interested in is a bit larger than 2500, you should choose Bicubic Sharper. To know more about resampling algorithms, check the link https://helpx.adobe.com/photoshop-elements/using/resizing.html#resample_an_image
As soon as you choose the "resample image" option, it would enable the pixel dimension area of the dialog.
change height(or width) to 2500 depending upon which side is the longest side.
click ok

How do you change the dpi settings in iPhoto

How do you change the dpi settings in iPhoto

Short answer: the dpi is set when you decide what size you're printing at.
Long Answer: Dpi means nothing in the digital world of your computer. There are no "inches" to have "dots per..." Size is measured in pixels. That's the same on your camera. It doesn't take 10 x 8 or 6 x 4 shots. It takes shots measured in megapixels. For instance 4,000 x 3,000 is a 12 megapixel camera.
Using that example, that shot from that camera has 12 million pixels. So that's how many "Dots" there are. To decide the ratio of dots per inch, you now need to decide the "inches" part. And that's printing. Print at 10 x 8 and the dpi will be 4,000/10 or about 400 dpi. At 6 x 4 then it's 4,000/6 or 660 dpi. Work the other way: Print at 300 dpi and the resulting image will be about 13 inches on the longer side.
So, your photo as a fixed number of pixels. Changing the dimensions of the print will vary the dpi, changing the dpi will vary the dimensions of the print.
For more see http://www.rideau-info.com/photos/mythdpi.html
Regards
TD

How can I change scanner dpi?

HP09430F C410 Photosmart - How can I change scanner settings to change the output resolution to 75 dpi and change the
size, too.
I am scanning fabric and EQ7 says to do this. EQ7 says, "Do NOT change image size-(which I tried in photoshop) as this rescales the image.
Thanks in advance.

lwalshrnc
Assuming a recent Version of Windows OS and that you have installed the Full Feature Software for the printer, the following may help.
More information on installing the Full Feature Software:
Install Full Feature Software – Printer
=============================================================================
After the Full Feature Software is installed, the Printer Assistant (previously the Solution Center) shortcut is likely installed on the Desktop.
Start the Printer Assistant > select Scan a Document or Photo >
Select Photo to File > Under Resolution, in the Drop down menu >
Adjust the dpi as desired > CHECK Show scan Preview (if desired) >
Click Scan
Example:
Click the Kudos Thumbs-Up to show you appreciate the help and time from our Experts.
Click Accept as Solution when the Answer is a good Fix or Workaround!
Although I strive to reflect HP's best practices, I do not work for HP.
Kind Regards,
Dragon-Fur

How do I adjust text size in toolbar, in tandem with browser text zoom, WITHOUT limiting the screen space of my browser window as a whole? Changing Windows DPI reduces browsability of window as displayed.

I tried to customize PC settings for my mom, whose site is failing. So I plugged in the nosquint Firefox addon and upped the font size. Additionally, I tried to make desktop text etc. (non-browser text) larger. When I accomplished this through the Windows DPI adjustment, the browser would not open to full screen width (at least, not through any means other than F11, which is something beyond my mother's understanding or patience). With DPI 120, the maximized browser will not go full screen, but will instead hold left of screen, and display less than the full width of the page being viewed (this make my mom give up. And who wants to scroll laterally anyways?). Is there some way to pair the functionality of Windows DPI boosts with Firefox text/window zoom? Thanks.
== This happened ==
Every time Firefox opened
== I changed Windows DPI to >196

See [[Toolbars and page content appear too large after upgrading to Firefox 3]]
Try to adjust the DPI setting, see [http://kb.mozillazine.org/layout.css.dpi layout.css.dpi]
Try to set the pref layout.css.devPixelsPerPx to 2 on the about:config page.
To open the ''about:config'' page, type '''about:config''' in the location (address) bar and press the Enter key, just like you type the url of a website to open a website.
If you see a warning then you can confirm that you want to access that page.

Changing Images at Runtime...it's sending me nuts (I'm a newbie, go easy)

Hi all,
I am trying change images at runtime and quite frankly it's driving me nuts. I'm pretty new to Java and don't understand some of the principles but I'm trying. I have this code below, that loads up a few images. I want to be able to change some/all of these images either on a timed even or on a button press, but all the things I've tried don't work. Can someone offer me some help....thanks in advance
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class bc extends JFrame implements ActionListener {
     public static void main(String[] args) {new bc();}
     bc() {
          //setUndecorated(true); // - this removed the titlebar!
                setTitle("BC...");
          setSize(350,125);
          setResizable(false);
          setLocation(50,50);
          setDefaultCloseOperation(EXIT_ON_CLOSE);
          setBackground(new Color(0,0,0));
          getContentPane().setBackground(new Color(255,255,255));
          JPanel hours = new JPanel();
          hours.setLayout(new GridLayout(4,2));
          hours.add(hour14);
          hours.add(hour24);
          hours.add(hour13);
          hours.add(hour23);
          hours.add(hour12);
          hours.add(hour22);
          hours.add(hour11);
          hours.add(hour21);
          JPanel mins = new JPanel();
          mins.setLayout(new GridLayout(4,2));
          mins.add(min14);
          mins.add(min24);
          mins.add(min13);
          mins.add(min23);
          mins.add(min12);
          mins.add(min22);
          mins.add(min11);
          mins.add(min21);
          JPanel secs = new JPanel();
          secs.setLayout(new GridLayout(4,2));
          secs.add(sec14);
          secs.add(sec24);
          secs.add(sec13);
          secs.add(sec23);
          secs.add(sec12);
          secs.add(sec22);
          secs.add(sec11);
          secs.add(sec21);
          JPanel helptext = new JPanel();
          helptext.setLayout(new GridLayout(4,2));
          helptext.add(new JLabel("8"));
          helptext.add(new JLabel("4"));
          helptext.add(new JLabel("2"));
          helptext.add(new JLabel("1"));
//add action listenters
          changeImg.addActionListener(this);
          JPanel cp = new JPanel();
          cp.setLayout(new GridLayout(1,6));
          cp.setBackground(new Color(255,255,255));
          cp.add(hours);
          cp.add(mins);
          cp.add(secs);
          cp.add(helptext);
          cp.add(changeImg);
          setContentPane(cp);
          setVisible(true);
     public void actionPerformed(ActionEvent ae) {
          hour11.PaintOff(1);
          //JOptionPane.showMessageDialog(this, "changed");
          repaint();
JPanel hour11 = new PaintOff(0);
JPanel hour12 = new PaintOff(0);
JPanel hour13 = new PaintBlank();
JPanel hour14 = new PaintBlank();
JPanel hour21 = new PaintOff(0);
JPanel hour22 = new PaintOff(0);
JPanel hour23 = new PaintBlank();
JPanel hour24 = new PaintBlank();
JPanel min11 = new PaintOff(0);
JPanel min12 = new PaintOff(0);
JPanel min13 = new PaintOff(0);
JPanel min14 = new PaintOff(0);
JPanel min21 = new PaintOff(0);
JPanel min22 = new PaintOff(0);
JPanel min23 = new PaintOff(0);
JPanel min24 = new PaintOff(0);
JPanel sec11 = new PaintOff(0);
JPanel sec12 = new PaintOff(0);
JPanel sec13 = new PaintOff(0);
JPanel sec14 = new PaintOff(0);
JPanel sec21 = new PaintOff(0);
JPanel sec22 = new PaintOff(0);
JPanel sec23 = new PaintOff(0);
JPanel sec24 = new PaintOff(0);
JButton changeImg = new JButton("change");
}///---------This is my PaintOff class ---------------\\\
import javax.swing.*;
import java.awt.*;
import java.awt.Image.*;
public class PaintOff extends JPanel {
Toolkit tk = Toolkit.getDefaultToolkit();
public Image imgOff = tk.getImage("off.jpg");
public Image imgOn = tk.getImage("on.jpg");
public Image paintMe = tk.getImage("off.jpg");
     PaintOff(int a) {
          if(a == 1) {
               vOn();
          } else {
               vOff();
     public void vOn() {
        paintMe = imgOn;
     //JOptionPane.showMessageDialog(new bc(), "shown");
     public void vOff() {
        paintMe = imgOff;
     public void paintComponent(Graphics g) {
          g.drawImage(paintMe,0,0,this);
}PaintBlank class is not included here, it's basically just the same as PaintOff but only has one image inside.
When I try and compile this code, I get
C:\jdk1.4\bin\bclock>javac bc.java
bc.java:79: cannot resolve symbol
symbol : method PaintOff (int)
location: class javax.swing.JPanel
hour11.PaintOff(1);
^
1 error
I don't understand this either, I've tried replacing "PaintOff(1)" with "vOn()" but I get the same error. This is baffling to be, as I thought that the hour11 would have access to all the methods inside the PaintOff class?
Anyway, thanks for any help you guys give me!
Cheers
//Chris.

Hi!
Your problem is that you've used a widening conversion to convert from PaintOff to a JPanel. JPanel has no such method, and so the compiler is complaining that it can't find it.
e.g
public class NoCompile{
     public static void main(String args[]){
          One one = new Two();
          one.methTwo();
public class Two extends One{
     public Two(){}
     public void methTwo(){
        System.out.println("Executed 2");
public class One{
     public One(){}
     public void meth1(){}
} will give you the same sort of error message. To make the compiler happy, use a cast.
Now this will compile and gives the right result.
public class NoCompile{
     public static void main(String args[]){
          One one = new Two();
          ((Two)one).methTwo();
}So in your case, you want to do
((PaintOff)hour11).vOn();
Does that help?
:) jen

How do you change the dpi in Illustrator and save as pdf?

I've created a file in Illustrator cs4 that I need to change the 350 dpi of and to save as a pdf before having it sent out to be printed. I've found ways to change the ppi...but will that do the same thing as changing the dpi? Any advice would be much appreciated!

This might explain it
http://forums.adobe.com/thread/370714
The device has the dpi not the file itself the file has a ppi resolution the screens are prepared in lpi.
The above explains it the highest resolution I have ever been asked for was 350 ppi for offset printing 300ppi is normal.
In other word you do not control the dpi as Steve mentions.

HOW TO SET IMAGE DPI

I read images which are 300 DPI . I get it in BufferedReader, and do some pixel manipulation. When I save those pics as PNG or JPEG the image DPI becomes 72 DPI. There should be a way to set image DPI when converting from Bufferedeader to .pgn or .jpg file.

I need to know how to set DPI to 400 without destroying the image data or pixel height and width. I know of two places within the header of a jpeg that this can be set a third I can see through debug information in metadata but cannot set. Why is this so difficult to manipulate?

Changing image dpi

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