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Thread: unable to match pixel size between merged jpgs

  1. #1
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    Default unable to match pixel size between merged jpgs

    Hi,
    I am trying to merge 2x logo jpeg images into a single side-by-side logo.
    I want to insert the new merged image into a box (in my invoicing software) that allows 400x120 pxl images.
    I have resized both images so that they are 120 pxl high (and less than 200 wide). However when I add them both into the same Irfanview file, one image is much smaller than the other. I thought they would be the same height because they are both 120 pxl high.
    After having several goes and trying a number of approaches, I have just noticed that the pixel size is listed differently in the Information panels?
    JPG1 shows the current size as: 122 x 120 Pixels (1.01)
    While JPG2 shows the current size as: 85 x 120 Pixels (0.70)
    I thought the pixel size was fixed according to the current setting of the display...????, but this appears not to be the case here!
    On screen, JPG2 looks to be only about half the height of JPG1, where I thought they should be exactly the same height.

    How can I adjust either or both of the images so that they are both exactly the same height at 120 pixels?

    Cheers,
    Greg

  2. #2
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    Default

    Did you use "Create Panorama Image" from the Image menu?

    Click image for larger version. 

Name:	Create Panorama Image.png 
Views:	122 
Size:	12.9 KB 
ID:	5350

    I merged this image 85x120

    Click image for larger version. 

Name:	85x120.png 
Views:	53 
Size:	6.1 KB 
ID:	5351
    with this image 122x120

    Click image for larger version. 

Name:	122x120.png 
Views:	118 
Size:	3.9 KB 
ID:	5352
    and got this resulting merged image

    Click image for larger version. 

Name:	Merged Images.png 
Views:	126 
Size:	8.0 KB 
ID:	5353

  3. #3
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    Default

    Hi and thanks for your suggestion.
    No, I did not do it that way. I used the "Paste Special (add on side)" option to add the second image to the file. However, the end result was pretty much the same.
    Here is the result using "Create Panorama Image"

    Click image for larger version. 

Name:	Irfinview-merge.JPG 
Views:	119 
Size:	15.9 KB 
ID:	5357

    What I am trying to achieve is to have both logos the same size, side-by-side.

    I think the problem is with the actual images. If you look at the Current Size filed in the Information panel fo rthe two images, they both have a number in brackets after the size in pixels. These two numbers are not the same and I think it is sort of a scaling or size ratio.

    Here are the two information panels, so you can see what I mean.

    Click image for larger version. 

Name:	JPEG1-Info.JPG 
Views:	60 
Size:	57.1 KB 
ID:	5358Click image for larger version. 

Name:	JPEG2-Info.JPG 
Views:	123 
Size:	56.1 KB 
ID:	5359

    BTW, your suggestion to use "Create Panorama Image" is much simpler than how I was doing it, but it hasn't solved my problem yet.

    Cheers,
    Greg

  4. #4
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    Default

    The (0.70) and (1.01) are just the aspect ratios of the images (rounded down).

    Are you using Windows scaling? Perhaps that is causing the buggy behaviour?

    I get the same result if I use Paste (from clipboard) to the right of the current image — the merged image is 207 x 120 pixels.

  5. #5
    Professional User Mij's Avatar
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    Default

    Hi, SurvivalMNC. I think you have a mistaken understanding of how image size and scaling work in Irfanview. I am sorry I do not have time just at present to explain it all in detail. Just stick to working in pixels for the moment as that is what both the Panorama and the Paste Special functions work with.

    Also when you make a screen capture of a displayed image, as you must have done to create the two images of the Information display in Post #3 above, remember that the size of the images (in pixels) that you create is the number of pixels of your screen that the image occupied when you did the capture. It is related to the size of the original image only through the zoom ratio you have applied to make the image appear the right size on the screen, and it is certainly not directly related at all to any data being displayed in an Information box that you captured.

    Both Panorama and Paste special work the same way when you add a second or subsequent image to the first one. They both automatically resize the second image to match the width or height of the common edge that they will both share.

    For Panaroma remember that you will need to enter the file names of all the images that you want to include. If you have edited an image in any way since you opened it then what you are currently looking at may not be the same as what will be added in your panorama unless you save the file again.
    For Paste Special what is added is what you saved on the clipboard. As you like shortcuts I assume you will do that using Ctrl+C. Remember though that if you have a selection box on screen you will only save to the clipboard what is inside the box .
    There are other pitfalls too if you are trying to add different versions of an image to the original one as you go through an editing function. Get to know what Ctrl+N, Ctrl+A, and of course Ctrl+C and Ctrl+V, can do for you as well (and holding down Ctrl when you click on the image can be handy too when cancelling a selection box).
    Last edited by Mij; 07.09.2018 at 10:45 AM.

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