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Posted

I do some PDF Edit applications like cropping the pages (Exported as Images and Imported Into Affinity Photo) on Affinity Photo.

 

I want to save the images after crop process with the same quality of the original file.

 

How can I do that?

Posted

What image format are you using?

In general, and in particular for JPG, the file does not contain any definitive "quality" information. And every time you Open a JPG and then save it, a bit of quality is lost even if you choose 100% in the Quality slider. Some programs make a guess at what quality level was used previously, but it is just a guess. I do not know what data in the image they use for that. But Affinity apps do not make that guess, and you must simply pick a value for Quality.

I would just use an image format that does not have such quality issues, like TIFF or PNG.

-- Walt
Designer, Photo, and Publisher V1 and V2 at latest retail and beta releases
PC:
    Desktop:  Windows 11 Pro 23H2, 64GB memory, AMD Ryzen 9 5900 12-Core @ 3.00 GHz, NVIDIA GeForce RTX 3090 

    Laptop:  Windows 11 Pro 23H2, 32GB memory, Intel Core i7-10750H @ 2.60GHz, Intel UHD Graphics Comet Lake GT2 and NVIDIA GeForce RTX 3070 Laptop GPU.
    Laptop 2: Windows 11 Pro 24H2,  16GB memory, Snapdragon(R) X Elite - X1E80100 - Qualcomm(R) Oryon(TM) 12 Core CPU 4.01 GHz, Qualcomm(R) Adreno(TM) X1-85 GPU
iPad:  iPad Pro M1, 12.9": iPadOS 18.3, Apple Pencil 2, Magic Keyboard 
Mac:  2023 M2 MacBook Air 15", 16GB memory, macOS Sequoia 15.0.1

Posted
2 hours ago, walt.farrell said:

What image format are you using?

In general, and in particular for JPG, the file does not contain any definitive "quality" information. And every time you Open a JPG and then save it, a bit of quality is lost even if you choose 100% in the Quality slider. Some programs make a guess at what quality level was used previously, but it is just a guess. I do not know what data in the image they use for that. But Affinity apps do not make that guess, and you must simply pick a value for Quality.

I would just use an image format that does not have such quality issues, like TIFF or PNG.

As suggested, TIFF and PNG are what I use for my Artworks. PNG is optimal for most cases

If truly wanting to make Prints or use a Printing Agency, TIFF is best.

The new JPEG XL couldn’t tell you about, as it exports as a .jxl file and cannot even open on iPad in Files or Photos to see any visual quality change.

Posted

You will probably only get that same file-size from Affinity if you export as JPG. And you will have to adjust the Quality slider down until you get a file-size you like, and then see if the image looks "good enough" to you.

Ideally you would start with something better than JPG. When you start with JPG, the quality can only decrease (I believe) because each time you save you lose some information.

-- Walt
Designer, Photo, and Publisher V1 and V2 at latest retail and beta releases
PC:
    Desktop:  Windows 11 Pro 23H2, 64GB memory, AMD Ryzen 9 5900 12-Core @ 3.00 GHz, NVIDIA GeForce RTX 3090 

    Laptop:  Windows 11 Pro 23H2, 32GB memory, Intel Core i7-10750H @ 2.60GHz, Intel UHD Graphics Comet Lake GT2 and NVIDIA GeForce RTX 3070 Laptop GPU.
    Laptop 2: Windows 11 Pro 24H2,  16GB memory, Snapdragon(R) X Elite - X1E80100 - Qualcomm(R) Oryon(TM) 12 Core CPU 4.01 GHz, Qualcomm(R) Adreno(TM) X1-85 GPU
iPad:  iPad Pro M1, 12.9": iPadOS 18.3, Apple Pencil 2, Magic Keyboard 
Mac:  2023 M2 MacBook Air 15", 16GB memory, macOS Sequoia 15.0.1

Posted

The Quality slider is only for JPEG exports, and only when Exporting (not when Saving).

-- Walt
Designer, Photo, and Publisher V1 and V2 at latest retail and beta releases
PC:
    Desktop:  Windows 11 Pro 23H2, 64GB memory, AMD Ryzen 9 5900 12-Core @ 3.00 GHz, NVIDIA GeForce RTX 3090 

    Laptop:  Windows 11 Pro 23H2, 32GB memory, Intel Core i7-10750H @ 2.60GHz, Intel UHD Graphics Comet Lake GT2 and NVIDIA GeForce RTX 3070 Laptop GPU.
    Laptop 2: Windows 11 Pro 24H2,  16GB memory, Snapdragon(R) X Elite - X1E80100 - Qualcomm(R) Oryon(TM) 12 Core CPU 4.01 GHz, Qualcomm(R) Adreno(TM) X1-85 GPU
iPad:  iPad Pro M1, 12.9": iPadOS 18.3, Apple Pencil 2, Magic Keyboard 
Mac:  2023 M2 MacBook Air 15", 16GB memory, macOS Sequoia 15.0.1

Posted
On 11/16/2022 at 9:05 AM, Mainecoon364 said:

How can I export It with the same quality and size?

That is simply technically impossible in case if jpeg files, and even more impossible when used within PDF files.

The jpeg format allows a variety of methods (algorithms, parameters, tables with pre-calculated values) to compress the file. It is not stored which method and parameters where used in jpeg files. So Apps have only 2 options:

  1. Do not touch the image content, copy the source data stream „as is“, work only on metadata level. There are a few apps allowing edits without re-coding the content, mainly for rotation and crop.
  2. All other apps decode the compressed data, and allow edits. For later save / export, the data must be freshly encoded (compressed), using the methods and parameters of that App and the user input. It is almost impossible to use the same encoding, and even when, the jpeg data can differ.
  3. PDF is a special case. It is a container format which uses JPEG compression, but does not store them as separate (embedded) files. It simply used the compression algorithms from JPEG, but stores the data in another way.

 

 

Mac mini M1 A2348 | MBP M3 

Windows 11 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5 | Dell 27“ 4K

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

I use iPad screenshots and videos even in the Desktop section of the forum when I expect no relevant difference.

 

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