Place embedded resolution query

[Karensa5E7B]

I create a new photoshop file with resolution of 300ppi, with a blank canvass I then place imbedded an image (JPG) that is 144dpi. When I then export as a JPG, the JPG is 300dpi despite the lower quality image (144dpi) being imbedded into it?? I assume the image quality will actually still be the lower resolution of 144dpi as this is whats making up the image, or will it transform any imbedded image to match the resolution setting of the original file (300ppi)?? I hope that makes sense.... Thanks 

[D Fosse]

Smart objects honor the physical print size. That defines a smart object and overrides everything else. This is for compatibility with vector applications like Illustrator.

This is a bit counter-intuitive for Photoshop users who are used to thinking in pixels, and it is non-native behavior for pixel-based images.

In any case, what it means in practice is what you observe: the lower-resolution image gets upsampled. When rasterized, the smart object "parent" resolution overrides all.

[Karensa5E7B]

I scanned in my original image as 300dpi as a pdf. When I copy and pasted it into MS Paint and exported as a JPEG it reduced to 144dpi. Now I place embedded it into 300ppi photoshop document its magically upsampled to 300dpi. I feel unsure that this will make it sufficient for printing or do I need to go back and scan as JPEGs and start the process again? If I open JPEG in MS Paint and edit it maintains the 300dpi. I have a lot of scans to do this with so would be good to know whether I need to. Thanks 

[JJMack]

Paste does not change the number of pixels being pasted  in nor change the Print resolution of the document the pixels are being pasted into. Print resolution is the size pixels are printed. The pixels in the PDF and the Pixels in the MS Paint document should be the same pixels.  Whet the PDF is printed it isdprinted  with pixels that are 1/300"x1/300"  in size where  the same Pixels are printed with pixel that are 1/44"x144" from the MS Paint document. The MS Paint print size is larger than the PDF print,  Both prints have the same pixels the prints have different sized printed pixels.

[Karensa5E7B]

Thanks for your reply. Ok so will place embedding the 144 file into a 300 photoshop file make it suitable for printing assuming none of what I've done should have affected the resolution anyway? 

[D Fosse]

Doing that will resample the file! Don't do that. You can't mix resolutions in smart objects, it will resample. Sooner or later everything inside the smart object will be rasterized for output or rendering, and then it will be rasterized to the master resolution.

Again, smart objects honor physical print size, not pixels. That's how smart objects were designed. That means you have to take some precautions to work with smart objects. One is to not mix different resolutions (unless you want the resampling and understand what's going on).

It might be worth refreshing what pixels per inch (ppi) is. It's not a property of the file. It's metadata instructions, used for printing. It tells how big each pixel will be on paper. The image itself is only pixels. It doesn't natively have a size, it doesn't natively have a resolution. It only has a number of pixels.

The pixels per inch instruction is added later to determine a print size. That is its only purpose! The fact that ppi is also used for some secondary functions like smart objects or font sizes (again, a physical size unit) shouldn't confuse you.

In this case you want to preserve your pixels. So you have two options: One, don't use smart objects. Just copy/paste. Two, if you really need this as a smart object, make sure the resolution matches the master smart object. You do this in Image > Image Size. Uncheck "resample"!! and set the desired ppi number. This doesn't change anything in the file, the pixels remain the same, but the print size changes inversely to the ppi number. The higher the ppi, the smaller the print size.

Understanding ppi is really simple: Just read "pixels per inch" literally. Read the words. That's all it means. No hidden meaning, no code. Just up front, how many pixels to an inch of paper.

[Karensa5E7B]

Thanks for taking the time to explain. 

The thing is I've copy and pasted from pdf into MS Paint (before I got photoshop) to make image right size. Then later got photoshop so opened the now 144dpi image in photoshop and edited it. When I exported it it maintained its 144dpi resolution. 

If I now copy and paste it into photoshop it would still be 144dpi. Whereas I want 300dpi for printing. So I think I need to go back to the pdf scan and copy and paste into photoshop instead with a file set to 300dpi. But will have to do all the editing again. Is that right?

Sorry if I'm still not getting it but this is all new to me. 

[Bojan Živković]

It is a bit confusing at first but keep asking and you will learn.

Image or document resolution can be altered without any lost of quality.

Resolution is number/information for printers and nothing else. What matters is how many pixels your image has. If you have enough pixels then 144 does not matter, you can change that number in Photoshop and you are good to go.

If on other side image does not have enough pixels it is wortless that resolution is set to even 600ppi. Print size is number of pixels divided by any number in resolution field. You need to set that number correctly to number which printer needs because and printer is also stupid machine and that's why you nned to take care of resolution, otherwise you can skip resolution and watch only pixel dimensions.

[Karensa5E7B]

Thanks. So to do that I just go to image>image size then enter resolution 300 and then convert the width and height back to previous values to keep the image size dimensions? This will save me a lot of work editing! 

[Bojan Živković]

Before changing Resolution uncheck Resample option then enter new value for resolution. Click OK to confirm and you are done. Next time when you need to downsample or upsample pixel dimensions ensure that Resample is checked.

[Test Screen Name]

"When I copy and pasted it into MS Paint" Don't do that! Really, don't do that!! Open the PDF direct in Photoshop. There are a lot of reasons here, but I'm just going to say no! no! no! This will DESTROY quality.

[JJMack]

When you place in your image file in the Smart object rendered pixels are your images pixels. It your image  not the layer pixels.  You may be filling the document canvas or just a portion of the canvas for how you are using the image in the documents composition.   Your image's pixels pixels in the hardened object will be transformed (interpolated)  into the canvas ares you using image in. The resulting pixels will be printed with pixel size print resolution.  So what is important is not the print resolution of the file being place is what is important is how many pixels are in the files image.  The initial scaling Place does is just a strange odd thing place does.  You will use the Interactive Place Transform to change the scaling place does or later use free transform to scale the smart object for how you want to use the image in the composite composition. The images pixels will be interpolated into the document canvas area the image is being user in.  Transforming a smart object layer is not a destructive process, The object is not changed the transform settings are just recorded into the smart object layer so the layer pixels can be generated. When you transform a smart object layer you are actually editing the recorded transform,  You are changing   how the object will be transform for the layers pixels. The smart object is not changed.

[barbara_a]

Photoshop can have only one resolution per file. The resolution of your photoshop file is 300ppi. Therefore the jpg will be upsampled to 300 ppi when it is placed into the 300ppi image.

[JJMack]

A document has only one resolution.  So if you create a new Photoshop Document with a 300DPI Print resolution all the layer in that document will have a 300DPI Print resolution.  Photoshop is a pixels editor.  Print Resolution is just a setting that set the size a document pixels will be printed.  There are severs ways to get images into your new document,  from others documents and files.  You cans copy and paste between documents, drag layers between documents and duplicate a layer into a different document.  In all these cases pixels are duplicate from one document to the other document.   Pixels are just duplicated into the documents,  the size those pixel will print depends on which document the pixels are in.  A image can be printed any size by changing the Print resolution the printed pixel size.

Now there is Photoshop's  "PLACE" it a strange beast.  Be default Place will create Smart object layers,    Photoshop will use the Image file composite Image' s pixels to create a hardened object.  That is just like a copy past or duplicate document images, The hardened object pixels can not be changed byt Photoshop tools.  However the hardened object is not the smart object layer pixels.  For me there is a big issues in Place.  If the Document the file is being place in has a different print resolution then the file being place in print resolution Place will scale the object degrade the image quality. If the scaled image does not fit within the document canvas Place may degrade the image a second time depending on you photoshop preferences resize during place.    The good news is the object has you image's actual pixels  your image quality can be recovered.  The Bad news is there are other Photoshop preferences for Place.

If you check Skip Transform when Placing there will be no interactive transform during Place. Photoshop will just do the rest of place. If you un-check Resize during Place the only resizing that will not be done is with layers larger the canvas size will not be scaled to fit on canvas. If you un-check Always Create Smart Object when Placing. There will be no hardened object to recovet quality.  You will not be able recover the degraded image lost quality.  Additional scaling will degrads even more.

Still Smart object layer are great. You just need to be careful with document print resolution.    IMO Photoshop scaling based on different print resolution is bogus. The User will scale the image in places interactive transform during place if the image needs to be scaled,  

[Test Screen Name]

Actually, I will try to explain. Reasons not to do this include

1. Saving as JPEG for later editing reduces quality. Avoid.

2. Pasting between apps often damaged quality. Avoid.

3. Pasting a PDF into Paint simply takes a screen shot NOT the original pixels. You might as well have scanned at screen resolution. Hugely damaging.

4. You may believe Paint can do something that Photoshop cannot. This is not true, but it may be quicker to learn Paint.

5. Paint will not keep colour profiles, so image colours may change.

6. PDF files DO NOT HAVE A RESOLUTION. Always keep this in mind. A PDF may contain pictures, and each one may have a different resolution, but no tool can tell you the resolution of a PDF, and any that do are just making up a number.

[Karensa5E7B]

Ok thanks. This has been a time costly lesson! 

But now if I open my pdf in photoshop it only has a resolution of 72ppi. If I change the resolution it changes the size of the image and I want to image size to be kept the same. It needs to be printed at size A6.

[Test Screen Name]

" if I open my pdf in photoshop it only has a resolution of 72ppi."

This is absolutely wrong, but I know exactly why you should say this; it seems right. Look at this screen shot:

This tricks many people. PDF is different from bitmap formats like JPEG, BMP, PNG (which, you will notice, do NOT offer a choice of ppi when you open). People simply assume that the resolution shown, 300 in my case, is the resolution of the PDF. But it's not because as I said PDF FILES DON'T HAVE A RESOLUTION. Rather, it's an invitation to CHOOSE the resolution you want. Certainly do NOT leave it as 72 ppi if you plan to print the result at its current size.

"If I change the resolution it changes the size of the image" Not if you set the resolution when you open it. Certainly if you use Image > Image Size it will do that, but this is the wrong thing, too late.

[Karensa5E7B]

Ok. But when I open the pdf file (File>open>select file from folder) it doesnt give me any option to change the resolution?? 

[JJMack]

If you do not get a Import dialog when you open the PDF  where you cans set canvas size and resolution your PDF is a Photoshop PDF a Photoshop layerd document. Photoshop will open the document as it was it was edited and saved in Photoshop. It has a canvas size and a print resolution that was saved.  You can use Photoshop features like Imags Size and Canvas size to  chang canvas size image size and resolution.   Acrobat PDF are not Photoshop PDF files the pages in the acrobat pdf need to be imported into Photoshop.